Self-assembled modified composite material, and preparation method therefor and use thereof

Abstract

A self-assembled modified composite material, and a preparation method therefor and the use thereof. The self-assembled modified composite material comprises modified desulfurized gypsum which uses fly ash as a carrier and a lanthanum-based material which is self-assembled and adsorbed onto the fly ash. The composite material has a good phosphorus removal effect and a low cost, and the efficiency of phosphorus removal can reach 99.9%; moreover, the composite material has a fluorine removal effect, and the removal rate of fluorine ions can reach 98%. In the composite material, the desulfurized gypsum is combined with the fly ash, and therefore the adsorption performance of the fly ash is effectively incorporated. Moreover, the lanthanum-based material is self-assembled onto the modified desulfurized gypsum which uses the fly ash as a carrier, thereby forming a composite material having a uniform coordination structure. The composite material has a relatively large specific surface area, which further enhances the adsorption performance of the composite material and broadens the application range thereof. Therefore, the comprehensive resource utilization of industrial waste residues is achieved, and a new direction is provided for the resource utilization of solid waste.

Description

A self-assembly modified composite material and its preparation method and application Technical Field

[0001] The present disclosure belongs to the technical field of comprehensive utilization of solid waste resources, and specifically relates to a self-assembled modified composite material and a preparation method and application thereof. Background Art

[0002] Phosphorus, a pollutant that contributes to eutrophication, has seen a rapid increase in the discharge of phosphorus-containing wastewater due to the rapid growth in the production and consumption of phosphorus-containing detergents and the development of phosphating technologies. Phosphorus in wastewater partially originates from agricultural waste; however, the extensive use of phosphorus-containing detergents in daily life has also significantly increased the phosphorus content in domestic wastewater. Furthermore, wastewater from industries such as phosphorus chemicals, fertilizers, papermaking, rubber, dyes and textile printing and dyeing, pesticides, coking, fermentation, and pharmaceuticals often contains phosphorus compounds. The discharge of high-phosphorus industrial wastewater into the natural environment contributes to the further eutrophication of water bodies. To protect the environment, businesses are increasing their investment in the treatment of phosphorus-rich wastewater. It is crucial to select economical, practical, and efficient phosphorus removal agents based on traditional process conditions.

[0003] Currently, wastewater phosphorus removal is primarily achieved through chemical precipitation. Chemical precipitation involves adding chemicals to wastewater, which, upon mixing with soluble salts such as phosphates, form granular, insoluble substances. Typical chemicals used include aluminum salts, iron salts (ferrous salts), lime, and iron-aluminum polymers. Chemical precipitation requires the addition of large amounts of flocculants, resulting in high treatment costs.

[0004] Therefore, it is of great research significance to prepare a low-cost and high-performance wastewater phosphorus removal material.

[0005] Summary of the Invention

[0006] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0007] In view of the deficiencies in the prior art, the purpose of the present disclosure is to provide a self-assembled modified composite material and its preparation method and application. The present disclosure has prepared a self-assembled modified composite material with excellent phosphorus removal effect and low cost, and its phosphorus removal efficiency can reach 99.9%. It also has the effect of removing fluorine, and the removal rate of fluoride ions can reach 98%. The present disclosure combines desulfurization gypsum with fly ash, effectively combining the adsorption properties of fly ash. When the composite material is applied to wastewater treatment, the precipitate produced by the chemical reaction can efficiently adsorb pollutants in the wastewater and accelerate its sedimentation, giving full play to the advantages of various solid wastes. In addition, the present disclosure self-assembles lanthanum-based materials onto modified desulfurization gypsum with fly ash as a carrier, forming a composite material with a uniform coordination structure, which has a large specific surface area, which further enhances the adsorption performance and application range of the composite material. The present disclosure realizes the comprehensive resource utilization of industrial waste residues, achieves the purpose of "waste treatment with waste", meets environmental requirements, and provides a new direction for the resource utilization of solid waste.

[0008] To achieve this purpose, the present disclosure adopts the following technical solutions:

[0009] In a first aspect, the present disclosure provides a self-assembled modified composite material, comprising modified desulfurization gypsum with fly ash as a carrier, and a lanthanum-based material self-assembled and adsorbed on the fly ash.

[0010] It should be noted that desulfurization gypsum is a solid waste produced simultaneously with flue gas desulfurization. Desulfurization gypsum is relatively fine, with a particle size generally not exceeding 90μm. Its main component is calcium sulfate dihydrate, with a content of more than 90%. Desulfurization gypsum also contains impurities such as calcium carbonate, calcium sulfite and soluble salts composed of sulfates or chlorides of sodium, potassium and magnesium.

[0011] It should be noted that fly ash is the fine ash collected from the flue gas after coal combustion and is the main solid waste discharged by coal-fired power plants. 2 / g, which makes it show higher adsorption performance.

[0012] It should be noted that desulfurization gypsum and fly ash are bulk solid wastes. Their large-scale storage occupies significant land resources, posing a threat to climate, soil, plants, and human health. By integrating their unique characteristics, research is underway to repurpose these solid wastes, transforming them into valuable resources. New composite materials have been developed and applied to wastewater treatment, achieving the goal of treating waste with waste, reducing treatment costs and providing new development opportunities.

[0013] Based on this, the present disclosure has prepared a self-assembled modified composite material with excellent phosphorus removal effect and low cost, the phosphorus removal efficiency of which can reach 99.9%, and it also has the effect of removing fluorine, and the removal rate of fluoride ions can reach 98%. The present disclosure combines desulfurization gypsum with fly ash, effectively combining the adsorption properties of fly ash. When the composite material is applied to wastewater treatment, the precipitate produced by the chemical reaction can efficiently adsorb pollutants in the wastewater and accelerate its sedimentation, giving full play to the advantages of various solid wastes. In addition, the present disclosure self-assembles lanthanum-based materials onto modified desulfurization gypsum with fly ash as a carrier, forming a composite material with a uniform coordination structure, which has a large specific surface area, which further enhances the adsorption performance and application range of the composite material. The present disclosure realizes the comprehensive resource utilization of industrial waste residues, achieves the purpose of "waste treatment with waste", meets environmental requirements, and provides a new direction for the resource utilization of solid waste.

[0014] As an optional technical solution of the present disclosure, the self-assembled modified composite material is a microspherical structure.

[0015] In the present disclosure, the self-assembled modified composite material of the microspherical structure helps to further improve its adsorption performance.

[0016] In one embodiment, the particle size D50 of the self-assembled modified composite material is 10-100 μm, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0017] In the present disclosure, the particle size D50 of the self-assembled modified composite material is in the range of 20-50 μm, which is more conducive to the dispersion and adsorption of the microsphere composite material.

[0018] As an optional technical solution of the present disclosure, based on the mass of the self-assembled modified composite material, the mass fraction of the lanthanum-based material is 1%-10%, for example, it can be 2.5%, 5%, 7.5% or 10%.

[0019] In the present disclosure, if the mass fraction of the lanthanum-based material is too small, the effective fluorine removal substances in the composite material are less and the performance is poor; if the mass fraction of the lanthanum-based material is too large, due to its low solubility, it cannot effectively self-assemble onto the modified desulfurization gypsum with fly ash as the carrier, the content of effective substances in the composite material will not increase, and the performance of the composite material will be difficult to be effectively improved, but will result in a waste of lanthanum-based materials.

[0020] In one embodiment, the lanthanum-based material includes any one of lanthanum sulfate, lanthanum nitrate, or lanthanum chloride, or a combination of at least two thereof.

[0021] The present disclosure can achieve the effect of fluorine removal by utilizing the principle that lanthanum-based materials and fluoride ions generate lanthanum fluoride precipitation.

[0022] As an optional technical solution of the present disclosure, based on the mass of the modified desulfurization gypsum with fly ash as the carrier, the mass fraction of the modified desulfurization gypsum is 10%-50%, for example, it can be 10%, 20%, 33% or 50%.

[0023] In the present disclosure, if the mass fraction of the modified desulfurization gypsum is too small, the calcium content participating in the reaction precipitation defluoridation is small, and the defluoridation effect is poor; if the mass fraction of the modified desulfurization gypsum is too large, the ratio of other effective agents such as lanthanum and fly ash is relatively reduced, and the comprehensive defluoridation performance of the composite material is reduced.

[0024] In one embodiment, the fly ash has a porous structure, and the porosity of the fly ash is 50%-80%, for example, 50%, 60%, 70% or 80%.

[0025] In this disclosure, fly ash has a large specific surface area and high adsorption activity, while the porous structure of the bead wall, with a porosity of 50-80%, has strong water absorption. Furthermore, the desulfurized gypsum and lanthanum-based materials self-assemble into the fly ash surface and pores, resulting in specific wastewater treatment properties.

[0026] In a second aspect, the present disclosure provides a method for preparing the self-assembled modified composite material according to the first aspect, the preparation method comprising the following steps:

[0027] The modified desulfurized gypsum with fly ash as a carrier and a lanthanum-based aqueous solution are mixed, subjected to a hydrothermal reaction, and calcined to obtain the assembled modified composite material.

[0028] The preparation method provided by the present invention has a simple process, and the main raw materials are solid waste (desulfurization gypsum, fly ash), which is low-cost. It realizes the comprehensive resource utilization of industrial waste residues and achieves the purpose of "treating waste with waste". At the same time, it meets environmental requirements and provides a new direction for the resource utilization of solid waste.

[0029] As an optional technical solution disclosed in the present invention, the solid-liquid ratio of the modified desulfurization gypsum with fly ash as the carrier and the lanthanum-based aqueous solution is (0.8-1.2) mg: (2-6) mL, wherein the selection range of the modified desulfurization gypsum with fly ash as the carrier "(0.8-1.2) mg" can be, for example, 0.8 mg, 0.9 mg, 1 mg, 1.1 mg or 1.2 mg, and the selection range of the lanthanum-based aqueous solution "(2-6) mL" can be, for example, 2 mL, 3 mL, 4 mL, 5 mL or 6 mL.

[0030] In the present disclosure, if the solid-liquid ratio of the modified desulfurization gypsum with fly ash as the carrier and the lanthanum-based aqueous solution is too large, that is, the content of the lanthanum-based aqueous solution is low, and the fluorine removal effect is poor; if the solid-liquid ratio of the modified desulfurization gypsum with fly ash as the carrier and the lanthanum-based aqueous solution is too small, then due to the limited adsorption capacity of the modified desulfurization gypsum with fly ash as the carrier, the content of the lanthanum-based material cannot be increased after adsorption saturation, resulting in the performance of the composite material cannot be improved, resulting in waste of lanthanum-based materials.

[0031] In one embodiment, the solute in the lanthanum-based aqueous solution includes any one of lanthanum sulfate, lanthanum nitrate, or lanthanum chloride, or a combination of at least two thereof.

[0032] In one embodiment, the mass ratio of the solute to the solvent in the lanthanum-based aqueous solution is (1-2): (100-200), wherein the selection range of the solute in the lanthanum-based aqueous solution "1-2" can be, for example, 1, 1.2, 1.4, 1.6, 1.8 or 2, and the selection range of the solvent in the lanthanum-based aqueous solution "100-200" can be, for example, 100, 120, 140, 160, 180 or 200, etc.

[0033] In the present disclosure, while ensuring that the solute is completely dissolved, the mass ratio of the solute is increased as much as possible, and the content of the effective substance is increased, which helps to increase the content of the lanthanum-based material self-assembled on the modified desulfurization gypsum with fly ash as the carrier, thereby enhancing the wastewater defluoridation ability of the composite material.

[0034] In one embodiment, the temperature of the hydrothermal reaction is 35-65°C, for example, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C or 65°C, and the time is 1-2h, for example, 1h, 1.2h, 1.4h, 1.6h, 1.8h or 2h, etc.

[0035] In the present disclosure, the hydrothermal reaction is carried out at 35-65°C for 1-2 hours. The lower the temperature, the higher the solubility of lanthanum sulfate. The higher the temperature, the faster its self-assembly adsorption onto the modified desulfurization gypsum with fly ash as the carrier can be increased. However, the temperature should not be too low or too high.

[0036] In one embodiment, the calcination temperature is 200-400°C, such as 200°C, 250°C, 300°C, 350°C or 400°C, and the calcination time is 20-60 min, such as 20 min, 30 min, 40 min, 50 min or 60 min.

[0037] In the present disclosure, if the calcination temperature is too low, the composite material cannot be effectively spherical and the substances cannot be effectively combined together; if the calcination temperature is too high, the effective substances in the relevant raw materials may decompose, resulting in a significant reduction in the performance of the composite material.

[0038] In one embodiment, the heating rate of the calcination is 2-3°C / min, for example, 2°C / min, 2.2°C / min, 2.4°C / min, 2.6°C / min, 2.8°C / min or 3°C / min.

[0039] As an optional technical solution of the present disclosure, the preparation method of the modified desulfurized gypsum includes:

[0040] The desulfurized gypsum raw material is washed with water, and then the washed desulfurized gypsum is mixed with a sulfuric acid aqueous solution and subjected to a water bath heating reaction to obtain the modified desulfurized gypsum.

[0041] In the present disclosure, the purpose of washing the desulfurized gypsum raw material is to remove impurities, and then the washed desulfurized gypsum is mixed with a sulfuric acid aqueous solution for hydrothermal reaction, which can further remove salts or impurities therein.

[0042] In one embodiment, the mass ratio of the washed desulfurized gypsum to the aqueous sulfuric acid solution is 1:(20-50), for example, it can be 1:20, 1:25, 1:30, 1:35, 1:40, 1:45 or 1:50.

[0043] In the present disclosure, the washed desulfurized gypsum is mixed with an aqueous sulfuric acid solution at a mass ratio of 1:(20-50) to remove salts or impurities therein and further purify the desulfurized gypsum.

[0044] In one embodiment, the aqueous sulfuric acid solution comprises 98% sulfuric acid and water, and the mass ratio of 98% sulfuric acid to water is (2-5):(20-50), for example, it can be 2:20, 2:50, 2:35, 3.5:35, 5:20 or 5:50, etc.

[0045] In one embodiment, the water bath heating reaction temperature is 80-90°C, such as 80°C, 82°C, 84°C, 86°C, 88°C or 90°C, and the time is 1-2h, such as 1h, 1.2h, 1.4h, 1.6h, 1.8h or 2h.

[0046] In the present disclosure, a water bath heating reaction is carried out at 80-90° C. for 1-2 hours to remove insoluble impurities and allow the lanthanum-based material to self-assemble onto the modified desulfurization gypsum with fly ash as the carrier.

[0047] As an optional technical solution of the present disclosure, the preparation method of the modified desulfurization gypsum using fly ash as a carrier includes:

[0048] The modified desulfurization gypsum and fly ash are mixed to obtain the modified desulfurization gypsum with fly ash as a carrier.

[0049] In the present disclosure, modified desulfurization gypsum and fly ash are mixed to obtain modified desulfurization gypsum with fly ash as the carrier, which effectively combines the adsorption properties of fly ash. When applied to wastewater treatment, the precipitate produced by the chemical reaction can efficiently adsorb pollutants in the solution and accelerate their sedimentation, giving full play to the advantages of various solid wastes.

[0050] In one embodiment, the mass ratio of the modified desulfurization gypsum and fly ash is (10-60): (60-100), wherein the selection range of the modified desulfurization gypsum "10-60" can be, for example, 10, 20, 30, 40, 50 or 60, and the selection range of the fly ash "60-100" can be, for example, 60, 70, 80, 90 or 100, etc.

[0051] In the present disclosure, the mass ratio of modified desulfurization gypsum and fly ash is (10-60):(60-100), which can effectively combine the wastewater treatment capacity of desulfurization gypsum with the adsorption capacity of fly ash.

[0052] In one embodiment, the fly ash is washed with water before being mixed with the modified desulfurization gypsum.

[0053] In the present disclosure, the purpose of first washing the fly ash with water is to remove impurities.

[0054] As an optional technical solution of the present disclosure, the preparation method includes the following steps:

[0055] (1) drying the desulfurized gypsum raw material at 100-120° C. (for example, 100° C., 105° C., 110° C., 115° C., or 120° C.), and then grinding it to a mesh size of 100-200 mesh (for example, 100 mesh, 150 mesh, or 200 mesh), and then mixing the ground desulfurized gypsum raw material with water in a mass ratio of 1:(3-5) (for example, 1:3, 1:4, or 1:5, etc.) to prepare a slurry, and stirring and washing at 70-90° C. for 20-40 min, and then filtering to obtain a filter residue, and then drying the filter residue at 100-120° C. (for example, 100° C., 105° C., 110° C., 115° C., or 120° C., etc.) and crushing and sieving to obtain washed desulfurized gypsum;

[0056] (2) mixing the washed desulfurized gypsum and aqueous sulfuric acid solution in a mass ratio of 1:(20-50), heating the mixture in a water bath at 80-90° C. for 1-2 h under stirring, and then filtering to obtain a filter residue, which is then dried and crushed and sieved at 100-120° C. (for example, 100° C., 105° C., 110° C., 115° C., or 120° C.) to obtain modified desulfurized gypsum;

[0057] (3) drying the fly ash at 100-120°C (for example, 100°C, 105°C, 110°C, 115°C or 120°C), grinding it to a mesh size of 100-200 mesh (for example, 100 mesh, 150 mesh, 200 mesh), mixing the ground fly ash with water in a mass ratio of 1:(3-5) (for example, 1:3, 1:4 or 1:5, etc.) to prepare a slurry, stirring and washing at 45-55°C for 30-50 minutes, and then filtering to obtain a filter residue, and then drying the filter residue at 100-120°C (for example, 100°C, 105°C, 110°C, 115°C or 120°C, etc.) and crushing and sieving to obtain washed fly ash;

[0058] (4) stirring and mixing the modified desulfurization gypsum and the washed fly ash in a mass ratio of (10-60): (60-100) to obtain a modified desulfurization gypsum with the fly ash as a carrier;

[0059] (5) Lanthanum sulfate and water are mixed in a mass ratio of (1-2): (100-200) to obtain a lanthanum-based aqueous solution, and then the modified desulfurization gypsum with fly ash as a carrier and the lanthanum-based aqueous solution are mixed in a solid-liquid ratio of (0.8-1.2) mg: (2-6) mL, and a hydrothermal reaction is carried out at 35-65 ° C for 1-2 hours, and then a soaking treatment is carried out for 24-48 hours (for example, 24 hours, 30 hours, 36 hours, 42 hours or 48 hours, etc.) ), filtering to obtain a filter residue, transferring the filter residue to an oven at 100-120°C (for example, 100°C, 105°C, 110°C, 115°C or 120°C, etc.) and drying for 2-4h (for example, 2h, 3h or 4h, etc.), and then calcining in a muffle furnace at a constant temperature of 200-400°C for 20-60min, with a heating rate of 2-3°C / min. After the calcination, cooling and grinding are carried out to obtain the self-assembled modified composite material.

[0060] The preparation method disclosed herein allows the lanthanum-based material to self-assemble onto the modified desulfurized gypsum with fly ash as the carrier, forming a microspherical composite material with a uniform coordination structure and a large specific surface area. The BET of the composite material is detected to be 4-10 m 2 / g, further enhancing the material's adsorption performance and application range. Furthermore, the preparation method is simple, and the main raw material is solid waste, which is low-cost. This method realizes the comprehensive resource utilization of industrial waste residues, achieving the goal of "waste treatment with waste" while meeting environmental requirements and providing a new direction for the resource utilization of solid waste.

[0061] In a third aspect, the present disclosure provides an application of the self-assembled modified composite material as described in the first aspect in the field of water treatment technology.

[0062] In the present disclosure, the self-assembled modified composite material can be widely used in wastewater treatment to effectively remove phosphorus in wastewater. For wastewater with a phosphorus content of 2200 mg / L, the addition of this composite material can reduce the total phosphorus to below 0.5 mg / L, and the phosphorus removal efficiency can reach 99.9%. The composite material also has a good effect on fluoride removal. Under optimal conditions, the fluoride ion removal rate can reach 98%.

[0063] The numerical range described in the present disclosure includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present disclosure no longer exhaustively lists the specific point values ​​included in the range.

[0064] Compared with the prior art, the present disclosure has the following beneficial effects:

[0065] (1) The present disclosure has prepared a self-assembled modified composite material with excellent phosphorus removal effect and low cost, and its phosphorus removal efficiency can reach 99.9%. It also has the effect of removing fluorine, and the removal rate of fluoride ions can reach 98%. The present disclosure combines desulfurization gypsum with fly ash, effectively combining the adsorption properties of fly ash. When the composite material is applied to wastewater treatment, the precipitate produced by the chemical reaction can efficiently adsorb pollutants in the wastewater and accelerate their sedimentation, giving full play to the advantages of various solid wastes. In addition, the present disclosure self-assembles lanthanum-based materials onto modified desulfurization gypsum with fly ash as a carrier, forming a composite material with a uniform coordination structure, which has a large specific surface area, which further enhances the adsorption performance and application range of the composite material.

[0066] (2) The self-assembled modified composite material prepared by the present invention can be widely used in wastewater treatment. For wastewater with a phosphorus content of about 2200 mg / L, the addition of this composite material can reduce the total phosphorus to below 0.5 mg / L, and the phosphorus removal efficiency can reach 99.9%.

[0067] (3) The preparation method provided by the present invention has a simple process and low cost, realizes the comprehensive resource utilization of industrial waste residues, achieves the purpose of "treating waste with waste", and at the same time meets environmental requirements, providing a new direction for the resource utilization of solid waste.

[0068] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0070] FIG1 is a SEM image of the self-assembled modified composite material prepared in Example 5 of the present disclosure. DETAILED DESCRIPTION

[0071] The technical solution of the present disclosure is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only used to help understand the present disclosure and should not be regarded as specific limitations of the present disclosure.

[0072] Example 1

[0073] This embodiment provides a self-assembled modified composite material, which includes modified desulfurized gypsum with fly ash as a carrier, and a lanthanum-based material self-assembled and adsorbed on the fly ash;

[0074] The self-assembled modified composite material is a microspherical structure, and the particle size D50 of the self-assembled modified composite material is 10 μm;

[0075] Based on the mass of the self-assembled modified composite material, the mass fraction of the lanthanum-based material is 2.5%, and the lanthanum-based material is lanthanum sulfate;

[0076] Based on the mass of the modified desulfurization gypsum with fly ash as a carrier, the mass fraction of the modified desulfurization gypsum is 20%, the fly ash has a porous structure, and the porosity of the fly ash is 65%.

[0077] This embodiment also provides a method for preparing the self-assembled modified composite material, which comprises the following steps:

[0078] (1) drying the desulfurized gypsum raw material at 105° C., grinding it to a mesh size of 100 mesh, mixing the ground desulfurized gypsum raw material with pure water in a mass ratio of 1:3 to prepare a slurry, heating it in a water bath to 80° C., stirring and washing it for 30 min, and then filtering it to obtain a filter residue. The filter residue was then dried and crushed at 105° C., sieved with a 100-mesh sieve, discarding the sieve-surface material, and taking the sieve-surface material to obtain washed desulfurized gypsum;

[0079] (2) The washed desulfurized gypsum was mixed with 98% sulfuric acid and water in a mass ratio of 1:4:40, and stirred in a water bath heated to 85°C for 2 h. The residue was then filtered to obtain a filter residue, which was then dried and crushed at 105°C. The residue was sieved with a 100-mesh sieve, the sieve-surface material was discarded, and the sieve-underside material was taken to obtain modified desulfurized gypsum;

[0080] (3) drying the fly ash at 105°C, grinding it to a mesh size of 100 mesh, mixing the ground fly ash with pure water in a mass ratio of 1:3 to prepare a slurry, heating it in a water bath at 50°C, stirring and washing it for 30 minutes, and then filtering it to obtain a filter residue. The filter residue was then dried and crushed at 105°C, sieved with a 100-mesh sieve, discarding the sieve-surface material, and taking the sieve-underface material to obtain water-washed fly ash;

[0081] (4) stirring and mixing the modified desulfurization gypsum and the washed fly ash in a mass ratio of 20:80 to obtain a modified desulfurization gypsum with fly ash as a carrier;

[0082] (5) Lanthanum sulfate and pure water are mixed at a mass ratio of 1:150 to obtain a lanthanum-based aqueous solution, and then the modified desulfurization gypsum with fly ash as the carrier and the lanthanum-based aqueous solution are mixed at a solid-liquid ratio of 1 mg:2.5 mL, and stirred in a water bath heated to 50°C for a constant temperature reaction for 1 hour, and then immersed for 24 hours, and filtered to obtain a filter residue, and the filter residue is transferred to an oven at 105°C and dried for 2 hours, and then calcined in a muffle furnace at a constant temperature of 250°C for 60 minutes, with a heating rate of 2°C / min. After the calcination is completed, it is placed in a dryer and naturally cooled and then ground to obtain the self-assembled modified composite material.

[0083] Example 2

[0084] This embodiment provides a self-assembled modified composite material, which includes modified desulfurized gypsum with fly ash as a carrier, and a lanthanum-based material self-assembled and adsorbed on the fly ash;

[0085] The self-assembled modified composite material is a microspherical structure, and the particle size D50 of the self-assembled modified composite material is 10 μm;

[0086] Based on the mass of the self-assembled modified composite material, the mass fraction of the lanthanum-based material is 5%, and the lanthanum-based material is lanthanum sulfate;

[0087] Based on the mass of the modified desulfurization gypsum with fly ash as a carrier, the mass fraction of the modified desulfurization gypsum is 33%, the fly ash has a porous structure, and the porosity of the fly ash is 65%.

[0088] This embodiment also provides a method for preparing the self-assembled modified composite material, which comprises the following steps:

[0089] (1) drying the desulfurized gypsum raw material at 105° C., grinding it to a mesh size of 100 mesh, mixing the ground desulfurized gypsum raw material with pure water in a mass ratio of 1:3 to prepare a slurry, heating it in a water bath to 80° C., stirring and washing it for 30 min, and then filtering it to obtain a filter residue. The filter residue was then dried and crushed at 105° C., sieved with a 100-mesh sieve, discarding the sieve-surface material, and taking the sieve-surface material to obtain washed desulfurized gypsum;

[0090] (2) The washed desulfurized gypsum was mixed with 98% sulfuric acid and water in a mass ratio of 1:3:30, and stirred in a water bath heated to 85°C for 2 h. The residue was then filtered to obtain a filter residue, which was then dried and crushed at 105°C. The residue was sieved with a 100-mesh sieve, the sieve-surface material was discarded, and the sieve-underside material was taken to obtain modified desulfurized gypsum;

[0091] (3) drying the fly ash at 105°C, grinding it to a mesh size of 100 mesh, mixing the ground fly ash with pure water in a mass ratio of 1:3 to prepare a slurry, heating it in a water bath at 50°C, stirring and washing it for 30 minutes, and then filtering it to obtain a filter residue. The filter residue was then dried and crushed at 105°C, sieved with a 100-mesh sieve, discarding the sieve-surface material, and taking the sieve-underface material to obtain water-washed fly ash;

[0092] (4) stirring and mixing the modified desulfurization gypsum and the washed fly ash in a mass ratio of 40:80 to obtain a modified desulfurization gypsum with fly ash as a carrier;

[0093] (5) Lanthanum sulfate and pure water are mixed at a mass ratio of 1:150 to obtain a lanthanum-based aqueous solution, and then the modified desulfurization gypsum with fly ash as the carrier and the lanthanum-based aqueous solution are mixed at a solid-liquid ratio of 1 mg:4 mL, and stirred in a water bath heated to 50°C for a constant temperature reaction for 1 hour, and then immersed for 24 hours, and filtered to obtain a filter residue, and the filter residue is transferred to an oven at 105°C and dried for 2 hours, and then calcined in a muffle furnace at a constant temperature of 350°C for 60 minutes, with a heating rate of 3°C / min. After the calcination is completed, it is placed in a dryer and naturally cooled and then ground to obtain the self-assembled modified composite material.

[0094] Example 3

[0095] This embodiment provides a self-assembled modified composite material, which includes modified desulfurized gypsum with fly ash as a carrier, and a lanthanum-based material self-assembled and adsorbed on the fly ash;

[0096] The self-assembled modified composite material is a microspherical structure, and the particle size D50 of the self-assembled modified composite material is 40 μm;

[0097] Based on the mass of the self-assembled modified composite material, the mass fraction of the lanthanum-based material is 10%, and the lanthanum-based material is lanthanum sulfate;

[0098] Based on the mass of the modified desulfurization gypsum with fly ash as a carrier, the mass fraction of the modified desulfurization gypsum is 33%, the fly ash has a porous structure, and the porosity of the fly ash is 65%.

[0099] This embodiment also provides a method for preparing the self-assembled modified composite material, which comprises the following steps:

[0100] (1) drying the desulfurized gypsum raw material at 105° C. and grinding it to a mesh size of 100 mesh. Then, mixing the ground desulfurized gypsum raw material with pure water in a mass ratio of 1:4 to prepare a slurry, heating it in a water bath to 80° C. and stirring and washing it for 30 min, and then filtering it to obtain a filter residue. Subsequently, drying and crushing the filter residue at 105° C., sieving it with a 100-mesh sieve, discarding the sieve-surface material, and taking the sieve-underface material to obtain washed desulfurized gypsum.

[0101] (2) The washed desulfurized gypsum was mixed with 98% sulfuric acid and water in a mass ratio of 1:3:30, and stirred in a water bath heated to 85°C for 2 h. The residue was then filtered to obtain a filter residue, which was then dried and crushed at 105°C. The residue was sieved with a 100-mesh sieve, the sieve-surface material was discarded, and the sieve-underside material was taken to obtain modified desulfurized gypsum;

[0102] (3) drying the fly ash at 105°C, grinding it to a mesh size of 100 mesh, mixing the ground fly ash with pure water in a mass ratio of 1:4 to prepare a slurry, heating it in a water bath at 50°C, stirring and washing it for 30 minutes, and then filtering it to obtain a filter residue. The filter residue was then dried and crushed at 105°C, sieved with a 100-mesh sieve, discarding the sieve-surface material, and taking the sieve-underface material to obtain water-washed fly ash;

[0103] (4) stirring and mixing the modified desulfurization gypsum and the washed fly ash in a mass ratio of 40:80 to obtain a modified desulfurization gypsum with fly ash as a carrier;

[0104] (5) Lanthanum sulfate and pure water are mixed at a mass ratio of 1:150 to obtain a lanthanum-based aqueous solution, and then the modified desulfurization gypsum with fly ash as the carrier and the lanthanum-based aqueous solution are mixed at a solid-liquid ratio of 1 mg:3 mL, and stirred in a water bath heated to 50°C for a constant temperature reaction for 1 hour, and then immersed for 24 hours, and filtered to obtain a filter residue, and the filter residue is transferred to an oven at 105°C and dried for 2 hours, and then calcined in a muffle furnace at a constant temperature of 250°C for 20 minutes, with a heating rate of 2°C / min. After the calcination is completed, it is placed in a dryer and naturally cooled and then ground to obtain the self-assembled modified composite material.

[0105] Example 4

[0106] This embodiment provides a self-assembled modified composite material, which includes modified desulfurized gypsum with fly ash as a carrier, and a lanthanum-based material self-assembled and adsorbed on the fly ash;

[0107] The self-assembled modified composite material is a microspherical structure, and the particle size D50 of the self-assembled modified composite material is 30 μm;

[0108] Based on the mass of the self-assembled modified composite material, the mass fraction of the lanthanum-based material is 5%, and the lanthanum-based material is lanthanum sulfate;

[0109] Based on the mass of the modified desulfurization gypsum with fly ash as a carrier, the mass fraction of the modified desulfurization gypsum is 33%, the fly ash has a porous structure, and the porosity of the fly ash is 65%.

[0110] This embodiment also provides a method for preparing the self-assembled modified composite material, which comprises the following steps:

[0111] (1) drying the desulfurized gypsum raw material at 105° C., grinding it to a mesh size of 100 mesh, mixing the ground desulfurized gypsum raw material with pure water in a mass ratio of 1:3 to prepare a slurry, heating it in a water bath to 80° C., stirring and washing it for 30 min, and then filtering it to obtain a filter residue. The filter residue was then dried and crushed at 105° C., sieved with a 100-mesh sieve, discarding the sieve-surface material, and taking the sieve-surface material to obtain washed desulfurized gypsum;

[0112] (2) The washed desulfurized gypsum was mixed with 98% sulfuric acid and water in a mass ratio of 1:2:18, and stirred in a water bath heated to 85°C for 2 hours, and then filtered to obtain a filter residue, which was then dried and crushed at 105°C, sieved with a 100-mesh sieve, and the sieve residue was discarded. The sieve residue was taken to obtain modified desulfurized gypsum;

[0113] (3) drying the fly ash at 105°C, grinding it to a mesh size of 100 mesh, mixing the ground fly ash with pure water in a mass ratio of 1:3 to prepare a slurry, heating it in a water bath at 55°C, stirring and washing it for 30 minutes, and then filtering it to obtain a filter residue. The filter residue was then dried and crushed at 105°C, sieved with a 100-mesh sieve, discarding the sieve-surface material, and taking the sieve-underface material to obtain water-washed fly ash;

[0114] (4) stirring and mixing the modified desulfurization gypsum and the washed fly ash at a mass ratio of 10:100 to obtain modified desulfurization gypsum with fly ash as a carrier;

[0115] (5) Lanthanum sulfate and pure water are mixed at a mass ratio of 1:200 to obtain a lanthanum-based aqueous solution, and then the modified desulfurization gypsum with fly ash as the carrier and the lanthanum-based aqueous solution are mixed at a solid-liquid ratio of 0.8 mg:6 mL, and stirred in a water bath heated to 50°C for a constant temperature reaction for 1 hour, and then immersed for 48 hours, and filtered to obtain a filter residue, and the filter residue is transferred to an oven at 105°C and dried for 2 hours, and then calcined in a muffle furnace at a constant temperature of 250°C for 40 minutes, with a heating rate of 2°C / min. After the calcination is completed, it is placed in a dryer and naturally cooled and then ground to obtain the self-assembled modified composite material.

[0116] Example 5

[0117] This embodiment provides a self-assembled modified composite material, which includes modified desulfurized gypsum with fly ash as a carrier, and a lanthanum-based material self-assembled and adsorbed on the fly ash;

[0118] The self-assembled modified composite material is a microspherical structure, and the particle size D50 of the self-assembled modified composite material is 20 μm;

[0119] Based on the mass of the self-assembled modified composite material, the mass fraction of the lanthanum-based material is 10%, and the lanthanum-based material is lanthanum sulfate;

[0120] Based on the mass of the modified desulfurization gypsum with fly ash as a carrier, the mass fraction of the modified desulfurization gypsum is 33%, the fly ash has a porous structure, and the porosity of the fly ash is 65%.

[0121] This embodiment also provides a method for preparing the self-assembled modified composite material, which comprises the following steps:

[0122] (1) drying the desulfurized gypsum raw material at 105° C., grinding it to a mesh size of 100 mesh, mixing the ground desulfurized gypsum raw material with pure water in a mass ratio of 1:5 to prepare a slurry, heating it in a water bath to 80° C., stirring and washing it for 30 min, and then filtering it to obtain a filter residue. The filter residue was then dried and crushed at 105° C., sieved with a 100-mesh sieve, discarding the sieve-surface material, and taking the sieve-underface material to obtain washed desulfurized gypsum;

[0123] (2) The washed desulfurized gypsum was mixed with 98% sulfuric acid and water in a mass ratio of 1:5:45, and stirred in a water bath heated to 85°C for 2 h. The residue was then filtered to obtain a filter residue, which was then dried and crushed at 105°C. The residue was sieved with a 100-mesh sieve, the sieve-surface material was discarded, and the sieve-underside material was taken to obtain modified desulfurized gypsum;

[0124] (3) drying the fly ash at 105°C, grinding it to a mesh size of 100 mesh, mixing the ground fly ash with pure water in a mass ratio of 1:5 to prepare a slurry, heating it in a water bath at 50°C and stirring and washing it for 30 minutes, then filtering it to obtain a filter residue, and then drying and crushing the filter residue at 105°C, sieving it with a 100-mesh sieve, discarding the sieve-surface material, and taking the sieve-underface material to obtain water-washed fly ash;

[0125] (4) stirring and mixing the modified desulfurization gypsum and the washed fly ash at a mass ratio of 60:60 to obtain a modified desulfurization gypsum with fly ash as a carrier;

[0126] (5) Lanthanum sulfate and pure water are mixed in a mass ratio of 2:100 to obtain a lanthanum-based aqueous solution, and then the modified desulfurization gypsum with fly ash as the carrier and the lanthanum-based aqueous solution are mixed in a solid-liquid ratio of 1.2 mg:2 mL, and stirred in a water bath heated to 50°C for a constant temperature reaction for 1 hour, and then immersed for 24 hours, and filtered to obtain a filter residue, and the filter residue is transferred to an oven at 105°C and dried for 2 hours, and then calcined in a muffle furnace at a constant temperature of 250°C for 40 minutes, with a heating rate of 2°C / min. After the calcination is completed, it is placed in a dryer and naturally cooled and then ground to obtain the self-assembled modified composite material.

[0127] Figure 1 shows an SEM image of the self-assembled modified composite material prepared in this example. As can be seen from the figure, the particle size of the self-assembled modified composite material is 20 μm, there are many tiny micropores on its surface, and particulate material can be observed adsorbed on the surface of the microspheres, indicating that the lanthanum-based material self-assembles and adsorbs onto the modified desulfurization gypsum with fly ash as the carrier.

[0128] Example 6

[0129] The difference between this embodiment and embodiment 5 is that the amount of the lanthanum-based aqueous solution added in step (5) is adjusted so that the mass fraction of the lanthanum-based material in the self-assembled modified composite material is 0.5%.

[0130] The rest of the preparation methods and parameters remained the same as in Example 5.

[0131] Example 7

[0132] The difference between this embodiment and embodiment 5 is that the amount of the lanthanum-based aqueous solution added in step (5) is adjusted so that the mass fraction of the lanthanum-based material in the self-assembled modified composite material is 20%.

[0133] The rest of the preparation methods and parameters remained the same as in Example 5.

[0134] Example 8

[0135] The difference between this embodiment and embodiment 5 is that the amount of modified desulfurization gypsum added in step (4) is adjusted so that the mass fraction of modified desulfurization gypsum in the modified desulfurization gypsum with fly ash as the carrier is 5%. The rest of the preparation method and parameters are the same as those in embodiment 5.

[0136] Example 9

[0137] The difference between this embodiment and embodiment 5 is that the amount of modified desulfurization gypsum added in step (4) is adjusted so that the mass fraction of the modified desulfurization gypsum in the modified desulfurization gypsum with fly ash as the carrier is 75%.

[0138] The rest of the preparation methods and parameters remained the same as in Example 5.

[0139] Example 10

[0140] The difference between this embodiment and embodiment 5 is that the calcination temperature in step (5) is 150°C.

[0141] The rest of the preparation methods and parameters remained the same as in Example 5.

[0142] Example 11

[0143] The difference between this embodiment and embodiment 5 is that the calcination temperature in step (5) is 450°C.

[0144] The rest of the preparation methods and parameters remained the same as in Example 5.

[0145] Comparative Example 1

[0146] The difference between this comparative example and Example 5 is that in step (5), no lanthanum-based aqueous solution is prepared, that is, lanthanum sulfate is not self-assembled onto the modified desulfurization gypsum with fly ash as the carrier.

[0147] The rest of the preparation methods and parameters remained the same as in Example 5.

[0148] Comparative Example 2

[0149] The difference between this comparative example and Example 5 is that steps (1) and (2) are not performed, that is, modified desulfurization gypsum is not prepared, but fly ash and lanthanum-based aqueous solution are directly mixed.

[0150] The rest of the preparation methods and parameters remained the same as in Example 5.

[0151] Comparative Example 3

[0152] The difference between this comparative example and Example 5 is that step (3) is not performed, that is, fly ash is not added, and the modified desulfurized gypsum and the lanthanum-based aqueous solution are directly mixed.

[0153] The rest of the preparation methods and parameters remained the same as in Example 5.

[0154] Performance Testing

[0155] 2 g of the self-assembled composite material obtained in the above embodiment and the composite material obtained in the comparative example were added to 100 mL of wastewater (TP concentration was 266.90 mg / L, fluoride ion concentration was 258.6 mg / L) to conduct fluoride and phosphorus removal effect experiments. The analysis and test results before and after the wastewater treatment are shown in Table 1 below.

[0156] Table 1

[0157] analyze:

[0158] As can be seen from Table 1 above, the self-assembled modified composite material prepared in the present disclosure can be widely used in wastewater treatment. When this composite material is added, the optimal phosphorus removal efficiency can reach 99.9%; at the same time, it also has a good fluorine removal effect.

[0159] It can be seen from Examples 5 and 6-7 that if the mass fraction of the lanthanum-based material in the self-assembled modified composite material is too small, the lanthanum-based salt content in the composite material is low, which will lead to a decrease in the performance of the composite material; if the mass fraction of the lanthanum-based material in the self-assembled modified composite material is too large, then due to its low solubility, it still cannot be effectively self-assembled onto the modified desulfurization gypsum with fly ash as the carrier, resulting in no significant change or improvement in its material performance, and at the same time causing waste of lanthanum-based materials.

[0160] It can be seen from Example 5 and Examples 8-9 that if the mass fraction of the modified desulfurization gypsum in the modified desulfurization gypsum with fly ash as the carrier is too small, the calcium content participating in the reaction precipitation and fluorine removal is relatively small, which will lead to a decrease in the performance of the composite material and poor fluorine removal effect; if the mass fraction of the modified desulfurization gypsum in the modified desulfurization gypsum with fly ash as the carrier is too large, the slightly soluble calcium sulfate content is relatively high, the defluorination reaction precipitation is not complete, the defluorination reaction precipitation is not complete, and the adsorption performance of the composite material is reduced.

[0161] It can be seen from Examples 5 and 10-11 that if the calcination temperature is too low, the composite material cannot be effectively sphered, resulting in a significant decrease in material performance; if the calcination temperature is too high, some substances in the composite material will decompose, which will also result in a significant decrease in material performance.

[0162] It can be seen from Example 5 and Comparative Example 1 that if lanthanum sulfate is not self-assembled onto the modified desulfurization gypsum with fly ash as a carrier, the effective substance is less, which will lead to a decrease in the wastewater treatment performance of the composite material.

[0163] It can be seen from Example 5 and Comparative Example 2 that if the modified desulfurization gypsum is not prepared but the fly ash and the lanthanum-based aqueous solution are directly mixed, the coagulation and sedimentation effect is poor, which will lead to a decrease in the wastewater treatment performance of the composite material.

[0164] It can be seen from Example 5 and Comparative Example 3 that if fly ash is not added and the modified desulfurization gypsum and the lanthanum-based aqueous solution are directly mixed, the adsorption performance is reduced, which will lead to a decrease in the wastewater treatment performance of the composite material.

[0165] In summary, the self-assembled composite material prepared in Example 5 has good phosphorus and fluoride removal effects. The composite material was further prepared according to Example 5, and a gradient experiment was carried out using materials of different masses. The materials were added to 100 mL of wastewater (TP concentration was 266.90 mg / L and fluoride ion concentration was 258.6 mg / L) to carry out fluoride and phosphorus removal effect experiments. The analysis and detection results before and after wastewater treatment are shown in Table 2 below.

[0166] Table 2

[0167] analyze:

[0168] As can be seen from Table 2 above, the self-assembled modified composite material prepared by the present invention can be widely used in wastewater treatment, and as the mass of the added composite material increases, the wastewater treatment effect becomes better. When 2 g is added, the phosphorus removal efficiency is the highest, reaching 99.9%, and it also has a good fluorine removal effect.

[0169] At the same time, a self-assembled modified composite material was further prepared according to Example 5 and applied to high-concentration phosphorus- and fluorine-containing wastewater. Gradient experiments were carried out using materials of different masses. The materials were added to 100 mL of wastewater (TP concentration was 2266.00 mg / L and fluoride ion concentration was 2152.00 mg / L) to perform fluorine removal and phosphorus removal effect experiments. The analysis and detection results before and after wastewater treatment are shown in Table 3 below.

[0170] Table 3

[0171] analyze:

[0172] As shown in Table 3 above, for high-concentration wastewater with phosphorus and fluorine contents of approximately 2200 mg / L, the addition of this composite material can reduce the total phosphorus to below 0.5 mg / L, and the phosphorus removal efficiency can reach 99.9%. At the same time, the composite material also has a good removal effect on fluoride. Under optimal conditions, the fluoride ion removal rate can reach 98%.

Claims

1. A self-assembled modified composite material, comprising modified desulfurized gypsum with fly ash as a carrier, and a lanthanum-based material self-assembled and adsorbed on the fly ash.

2. The self-assembled modified composite material according to claim 1, wherein The self-assembled modified composite material is in a microsphere structure.

3. The self-assembled modified composite material according to claim 1 or 2, wherein, The particle size D50 of the self-assembled modified composite material is 10 - 100 μm.

4. The self-assembled modified composite material according to any one of claims 1-3, wherein, Based on the mass of the self-assembled modified composite material, the mass fraction of the lanthanum-based material is 1% - 10%.

5. The self-assembled modified composite material according to any one of claims 1-4, wherein, The lanthanum-based material includes any one or a combination of at least two of lanthanum sulfate, lanthanum nitrate, or lanthanum chloride.

6. The self-assembled modified composite material according to any one of claims 1-5, wherein, Based on the mass of the modified desulfurized gypsum with fly ash as a carrier, the mass fraction of the modified desulfurized gypsum is 10% - 50%.

7. The self-assembled modified composite material according to any one of claims 1-6, wherein, The fly ash is in a porous structure, and the porosity of the fly ash is 50% - 80%.

8. A preparation method of the self-assembled modified composite material according to any one of claims 1 - 7, comprising the following steps: Mix the modified desulfurized gypsum with fly ash as a carrier and an aqueous lanthanum-based solution, conduct a hydrothermal reaction, and obtain the assembled modified composite material after calcination.

9. The preparation method according to claim 8, wherein The solid-liquid ratio of the modified desulfurized gypsum with fly ash as a carrier and the aqueous lanthanum-based solution is (0.8 - 1.2) mg : (2 - 6) mL.

10. The preparation method according to claim 8 or 9, wherein, The mass ratio of the solute to the solvent in the aqueous lanthanum-based solution is (1 - 2) : (100 - 200).

11. According to the preparation method according to any one of claims 8-10, wherein, The temperature of the hydrothermal reaction is 35 - 65 °C, and the time is 1 - 2 h.

12. The preparation method according to any one of claims 8-11, wherein, The temperature of the calcination is 200 - 400 °C, and the time is 20 - 60 min.

13. The preparation method according to any one of claims 8-12, wherein, The preparation method of the modified desulfurized gypsum includes: Wash the desulfurized gypsum raw material, then mix the washed desulfurized gypsum and sulfuric acid aqueous solution, and conduct a water bath heating reaction to obtain the modified desulfurized gypsum; Optionally, the mass ratio of the washed desulfurized gypsum to the sulfuric acid aqueous solution is 1 : (20 - 50); Optionally, the temperature of the water bath heating reaction is 80 - 90 °C, and the time is 1 - 2 h.

14. The preparation method according to any one of claims 8-13, wherein, The preparation method of the modified desulfurized gypsum with fly ash as a carrier includes: Mix the modified desulfurized gypsum and fly ash to obtain the modified desulfurized gypsum with fly ash as a carrier; Optionally, the mass ratio of the modified desulfurized gypsum to the fly ash is (10 - 60) : (60 - 100); Optionally, before mixing the fly ash and the modified desulfurized gypsum, wash the fly ash first.

15. The preparation method according to any one of claims 8-14, wherein, The preparation method includes the following steps: (1) Dry the desulfurized gypsum raw material at 100 - 120 °C, then grind it to a mesh number of 100 - 200 mesh, then mix the ground desulfurized gypsum raw material and water according to a mass ratio of 1 : (3 - 5) to make a slurry, and stir and wash at 70 - 90 °C for 20 - 40 min, then filter to obtain a filter residue, and then dry and crush and screen the filter residue at 100 - 120 °C to obtain the washed desulfurized gypsum; (2) Mix the washed desulfurized gypsum and sulfuric acid aqueous solution according to a mass ratio of 1 : (20 - 50), conduct a water bath heating reaction at 80 - 90 °C for 1 - 2 h under stirring conditions, then filter to obtain a filter residue, and then Dry and crush and screen the filter residue at 100 - 120 °C to obtain the modified desulfurized gypsum; (3) Dry the fly ash at 100 - 120 °C, then grind it to a mesh size of 100 - 200 mesh. Then, mix the ground fly ash and water at a mass ratio of 1:(3 - 5) to make a slurry, and stir and wash it at 45 - 55 °C for 30 - 50 min. Then, filter to obtain the filter residue. Subsequently, dry and crush and screen the filter residue at 100 - 120 °C to obtain the washed fly ash; (4) Stir and mix the modified desulfurized gypsum and the washed fly ash at a mass ratio of (10 - 60):(60 - 100) to obtain the modified desulfurized gypsum with fly ash as the carrier; (5) Mix lanthanum sulfate and water at a mass ratio of (1 - 2):(100 - 200) to obtain a lanthanum-based aqueous solution. Then, mix the modified desulfurized gypsum with fly ash as the carrier and the lanthanum-based aqueous solution at a solid-liquid ratio of (0.8 - 1.2) mg:(2 - 6) mL, and carry out a hydrothermal reaction at 35 - 65 °C for 1 - 2 h. Then, carry out an immersion treatment for 24 - 48 h, filter to obtain the filter residue. Transfer the filter residue to an oven at 100 - 120 °C and dry it for 2 - 4 h. Then, carry out a constant-temperature calcination in a muffle furnace at 200 - 400 °C for 20 - 60 min. The heating rate of the calcination is 2 - 3 °C / min. After the calcination is completed, carry out cooling and grinding to obtain the self-assembled modified composite material.

16. Application of a self-assembled modified composite material as described in any one of claims 1 - 7 in the field of water treatment technology.

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