Method for synergistically preparing high-performance adsorption material from electrolytic aluminum overhaul slag and red mud and application of high-performance adsorption material
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-04
- Publication Date
- 2026-04-14
Smart Images
Figure CN121847079A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the interdisciplinary field of solid waste co-resource utilization and environmental functional materials, specifically involving a method for preparing high-performance adsorbent materials by co-processing electrolytic aluminum overhaul slag and red mud, and its application. Background Technology
[0002] Electrolytic aluminum overhaul slag is a typical hazardous waste generated during maintenance in the electrolytic aluminum industry. It contains fluorides (15%-30%), cyanides (0.5%-2%), and carbon resources (10%-20%). Traditional landfill disposal can easily cause fluoride leakage and cyanide pollution.
[0003] Red mud is a major hazardous waste produced by alumina production, with an annual discharge of over 100 million tons. It is rich in metal oxides such as Al2O3 (15%-30%), Fe2O3 (10%-20%), and CaO (20%-30%). However, due to its complex composition and low activity, its resource utilization rate is less than 5%, resulting in low added value.
[0004] In the electrolytic aluminum production process, common technologies for the harmless treatment of overhaul slag include rotary kiln charring and acid-free wet processing, which can effectively transform harmful substances in the slag into highly stable solids. However, these technologies are costly to implement; for example, the treatment cost of rotary kiln charring is approximately 2000 yuan / ton. Furthermore, the preparation of solid waste-based adsorbent materials is often limited by the use of a single solid waste, resulting in low adsorption capacity (Cu2+ adsorption capacity ≤80mg / g), poor selectivity, and insufficient stability.
[0005] Currently, there are no reports on the synergistic preparation of multifunctional adsorbent materials from electrolytic aluminum overhaul slag and red mud using a "detoxification-pore-forming-bimetallic synergistic loading" process. Existing materials cannot meet the demands for high-capacity, high-selectivity, and long-life adsorbents in the deep treatment of complex wastewater. Therefore, developing a synergistic preparation technology that can achieve full resource utilization of both hazardous wastes and exhibit excellent adsorption performance has significant economic and environmental value. Summary of the Invention
[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing high-performance adsorbent materials by synergistically combining electrolytic aluminum overhaul slag and red mud, and its application. This method achieves a comprehensive utilization rate of over 98% for electrolytic aluminum overhaul slag and red mud. The prepared high-performance adsorbent material effectively removes cyanide from the overhaul slag, directionally converts fluorine resources into adsorption active sites, effectively adsorbs heavy metals such as Cu2+ and Pb2+ and fluorides, and can be regenerated and recycled. The entire process is free of secondary pollution, and the preparation cost of the adsorbent material is low, achieving the dual goals of "treating waste with waste and turning waste into treasure".
[0007] The technical solution of this invention is as follows: A method for synergistically preparing high-performance adsorbent materials from electrolytic aluminum overhaul slag and red mud, comprising the following steps: (1) Refined pretreatment and detoxification of electrolytic aluminum overhaul slag: S1. Pretreatment of electrolytic aluminum overhaul slag: Take electrolytic aluminum overhaul slag, crush and ball mill for 3-7 hours, sieve to obtain 150-200 mesh powder, and after gradient roasting and detoxification, obtain roasted overhaul slag. S2. Red mud pretreatment: Red mud is dried, crushed, ball-milled, sieved, and acid-etched to obtain activated red mud powder. S3. Mixing and Batching: Mix the roasted overhaul residue and activated red mud powder at a mass ratio of 1:1.5-2.5 for 30-40 minutes to obtain mixed raw materials; (2) Composite alkali gradient activation pore formation: SS1, Preparation of Activator: Calcium carbonate, sodium hydroxide and polyvinyl alcohol are mixed and ground in a mass ratio of 3.0-5.0:1.6-2.4:0.8-1.2 to obtain a composite alkali activator; SS2, Activation: Add 25-30% of the total mass of the compound alkali activator to the mixed raw materials, adjust the moisture content to 32-38%, age at room temperature for 16-24 hours, and then perform gradient temperature activation in a nitrogen atmosphere to obtain the activated product; Washing and purification combined with bimetallic ion synergistic loading: SSS1, Washing and Purification: The activated product is washed with water until pH=6.8-7.2, then soaked in 5% hydrochloric acid for 20-35 min, washed again with water until pH=6.5-7.5, and vacuum dried at 105-115℃ for 5.5-8 h to obtain a porous support. SSS2, Bimetallic Support: After mixing the porous support with the ferric nitrate-lanthanum nitrate composite metal salt solution, the mixture is first subjected to a mixing reaction and then filtered. The filtrate is discarded and the filter residue is collected. The ferric nitrate-lanthanum nitrate composite metal salt solution contains Fe3+ concentration of 0.6-0.9 mol / L and La3+ concentration of 0.2-0.3 mol / L, with Fe3+:La3+ = 2-4:1. SSS3, solidification and calcination: The filter residue is subjected to solidification gradient calcination to obtain high-performance composite adsorption materials.
[0008] In the aforementioned method, in step (1), S1, the gradient roasting procedure for the electrolytic aluminum overhaul slag is as follows: at room temperature, the temperature is increased to 300℃ at a heating rate of 5℃ / min and held for 1h, then increased to 450℃ at a heating rate of 8℃ / min and held for 1.5h, and finally increased to 550-600℃ at a heating rate of 10℃ / min and held for 2-2.5h.
[0009] In the aforementioned method, in step (1), S2, the red mud pretreatment is performed as follows: red mud is dried at 105-110℃ for 4-6 hours, crushed and ball-milled for 4-6 hours, sieved to obtain 150-170 mesh powder, acid-etched and activated with 2.5-3.5% hydrochloric acid solution for 1.0-1.5 hours, washed to pH 5-7, and dried at 100-120℃ for 1-2 hours to obtain activated red mud powder.
[0010] In the aforementioned method, step (2), SS1, the composite alkali activator is a mixture of calcium carbonate, sodium hydroxide, and polyvinyl alcohol in a mass ratio of 4:2:1.
[0011] In the aforementioned method, step (2), SS2, the gradient activation procedure is as follows: at room temperature, the temperature is increased to 200-400℃ at a heating rate of 5℃ / min and held for 1h, then increased to 500-700℃ at a heating rate of 8℃ / min and held for 1.5-2h, the nitrogen flow rate is 1.0-1.5L / min, and the specific surface area of the activated product is ≥300m² / g.
[0012] In the aforementioned method, in step (3), SSS2, the solid-liquid ratio of the porous carrier to the composite metal salt solution is 1:6-9, the mixing reaction temperature is 70-80℃, the mixing reaction time is 2.5-3.5h, and the mixing stirring rate is 200-250r / min.
[0013] In the aforementioned method, step (3), SSS3, the curing gradient calcination procedure is to keep the temperature at 300℃ for 1 hour, and then raise the temperature to 420-480℃ and keep it at 420-480℃ for 1.5-2 hours.
[0014] The aforementioned high-performance adsorbent material is used to treat heavy metals and fluorides in industrial wastewater. The treatment conditions for industrial wastewater by the high-performance adsorbent material are: space velocity 1-2 h⁻¹, temperature 25-35℃, and pH=5-7.
[0015] The aforementioned high-performance adsorbent material is used to treat heavy metals and fluorides in industrial wastewater. After treating the industrial wastewater, the high-performance adsorbent material can be regenerated and recycled using an acid-alkali washing composite process. The regeneration process involves soaking the material in 0.5 mol / L hydrochloric acid for 1 hour, followed by soaking it in 0.3 mol / L sodium hydroxide for 30 minutes.
[0016] The aforementioned high-performance adsorbent material is used in the treatment of heavy metals and fluorides in industrial wastewater. The high-performance adsorbent material has a regeneration rate of ≥90% and can be recycled ≥12 times.
[0017] Technical Principles The core technical principle of this invention is a three-level enhancement mechanism of "porous framework - active sites - synergistic adsorption", as detailed below: 1. Synergistic pore-forming mechanism: The carbon resources of the electrolytic aluminum overhaul slag are activated by composite alkali to form a porous carbon framework. The metal oxides (Al2O3, Fe2O3, CaO) of red mud fill the pores, forming a "carbon-metal oxide" composite carrier. During the activation process, the composite alkali reacts with SiO2 and Al2O3 to generate soluble silicates and aluminates. After elution, a rich microporous-mesoporous structure is formed, providing physical space for adsorption. 2. Bimetallic active site mechanism: Fe3+ is loaded to form Fe2O3, which captures heavy metal ions through "chemisorption-complexation precipitation" (e.g., Cu2++Fe2O3→CuO·Fe2O3); La3+ is converted to La2O3, which forms a stable LaF3 precipitate with fluoride (La3++3F⁻→LaF3↓). At the same time, CaO and Al2O3 in red mud assist in the adsorption of fluoride, achieving simultaneous removal of heavy metals and fluoride. 3. Synergistic adsorption mechanism: The physical retention of pollutants by the porous carbon framework concentrates pollutants, while the chemical adsorption of metal oxides and the complexation / precipitation of bimetallic ions enhance removal. These three factors do not compete or interfere with each other and promote each other, significantly improving adsorption capacity and selectivity.
[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention achieves the synergistic conversion of electrolytic aluminum overhaul slag and red mud through the full resource utilization of two hazardous wastes, with a utilization rate of ≥98% and a cyanide removal rate of ≥99.5%. One ton of material can absorb 0.45-0.55 tons of overhaul slag and 0.8-1.0 tons of red mud. The novel adsorbent material, through the synergistic loading of two metal ions, achieves adsorption capacities of ≥200 mg / g for Cu2+, ≥250 mg / g for Pb2+, and ≥80 mg / g for F⁻. The simultaneous removal rate of heavy metals and fluorides is ≥99%, which is 2.5-4 times that of traditional materials, and maintains ≥95% selectivity in high-salt systems.
[0019] 2. The high-performance adsorbent material prepared by this invention has stable performance in the range of pH=3-9 and total salt content ≤15%, with a regeneration rate ≥90%, and can be recycled ≥12 times. After 12 cycles, the capacity is maintained at more than 85%.
[0020] 3. The preparation process is green, with no secondary pollution throughout, and energy consumption is 60% of that of traditional methods, with a daily production capacity of 8-12 tons. The cost is 1800-2500 yuan / ton, far lower than commercial materials. It is suitable for the purification of wastewater and drinking water in industries such as metallurgy and electroplating, achieving the dual goals of "treating waste with waste and turning waste into treasure". Attached Figure Description
[0021] Figure 1 Flowchart of the preparation process for high-performance adsorption materials. Detailed Implementation
[0022] The present invention will be further described below with reference to embodiments. These embodiments are merely supplementary explanations and illustrations of the present invention, and not intended to limit the invention.
[0023] The electrolytic aluminum overhaul slag used in the following examples and comparative examples is solid waste produced by electrolytic aluminum plants, and the red mud is solid waste produced by alumina plants.
[0024] Example 1 1. Preparation process of high-performance adsorbent materials: (1) Refined pretreatment and detoxification of raw materials: S1. Pretreatment of electrolytic aluminum overhaul slag: Take 5 kg of electrolytic aluminum overhaul slag (composition: fluoride 22%, cyanide 1.2%, fixed carbon 16%, other 59.8%), crush and ball mill for 3 h, and sieve to obtain 180 mesh powder (D50=70μm, D90=95μm); gradient roasting: room temperature → 300℃ (5℃ / min, holding for 1 h) → 450℃ (8℃ / min, holding for 1.5 h) → 600℃ (10℃ / min, holding for 2.2 h) to obtain 4.2 kg of roasted overhaul slag (cyanide removal rate 99.6%, fluorine conversion rate 91%).
[0025] S2. Red mud pretreatment: Take 10 kg of red mud (composition: Al2O3 25%, Fe2O3 18%, CaO 28%, SiO2 8%, other 21%), dry at 108℃ for 5 h, crush and ball mill for 5 h, and sieve to obtain 150 mesh powder; acid etch activation with 3% hydrochloric acid solution for 1.2 h, wash to pH 6, and dry at 120℃ for 2 h to obtain 8.5 kg of activated red mud.
[0026] S3. Mixing and Batching: Mix roasted overhaul residue (4.2 kg) and activated red mud (8.4 kg) at a mass ratio of 1:2 and mix for 35 min to obtain 12.663 kg of mixed raw materials.
[0027] (2) Composite alkali gradient activation pore formation: SS1, Preparation of Activator: 4 kg of calcium carbonate, 2 kg of sodium hydroxide, and 1 kg of polyvinyl alcohol are ground and mixed to obtain 7 kg of composite alkali activator; SS2, Activation: Add 28% of the total mass of the mixed raw materials with a composite alkali activator (3.546 kg), spray water to adjust the moisture content to 35%, and age at room temperature for 20 h; then transfer to a tube furnace for gradient temperature activation. The nitrogen flow rate in the tube furnace is 1.2 L / min, and the gradient temperature is: room temperature → 300℃ (5℃ / min, hold for 1 h) → 600℃ (8℃ / min, hold for 2 h), to obtain 9.8 kg of activated product (specific surface area 320 m² / g, total pore volume 0.38 cm³ / g).
[0028] (3) Washing and purification combined with bimetallic ion synergistic loading SSS1, Washing and Purification: The activated product was washed to pH=7.2, soaked in 5% hydrochloric acid for 30 min, and washed again to pH=6.5-7.5; vacuum dried at 112℃ for 7 h to obtain 8.2 kg of porous carrier (specific surface area 380 m² / g). SSS2, Bimetallic Support: Prepare a composite salt solution (0.75 mol / L ferric nitrate + 0.25 mol / L lanthanum nitrate), mix the porous support and the solution at a solid-liquid ratio of 1:7, stir at 75℃ and 210 r / min for 3 h, filter, discard the filtrate, and collect the filter residue; SSS3, Curing Gradient Calcination: The filter residue was kept at 300℃ for 1 hour and then at 450℃ for 1.8 hours to obtain 8.5 kg of high-performance adsorbent material.
[0029] 2. Performance testing and application testing; High-performance adsorbent material properties: specific surface area 395 m² / g, total pore volume 0.42 cm³ / g, Fe₂O₃ loading 6.8 wt%, La₂O₃ loading 2.2 wt%; Adsorption performance: The adsorption capacity for Cu2+ can reach 215 mg / g, and the adsorption capacity for Pb2+ can reach 268 mg / g, showing high adsorption efficiency for these heavy metal ions.
[0030] Application Testing: The adsorption material was used to treat specific complex wastewater (Cu2+ 100mg / L, Pb2+ 60mg / L, F⁻ 50mg / L, total salt 10%). Under conditions of 30℃ and pH=6.0, after adding the adsorption material and stirring for 1 hour, the Cu2+ concentration was reduced to 0.07mg / L, the Pb2+ concentration to 0.05mg / L, and the F⁻ concentration to 0.3mg / L, with corresponding removal rates of 99.93%, 99.92%, and 99.4%, respectively.
[0031] 3. Regeneration performance: Regeneration can be performed using 5% dilute hydrochloric acid. After 12 regeneration cycles, the adsorption capacity of Cu2+ remained at 185 mg / g, equivalent to 86% of the initial adsorption capacity; the adsorption capacity of F⁻ also remained at 73 mg / g, also 86% of the initial value.
[0032] Example 2 Preparation process of high-performance adsorbent materials: Refined pretreatment and detoxification of raw materials S1. Pretreatment of electrolytic aluminum overhaul slag: Take 5 kg of electrolytic aluminum overhaul slag (composition: fluoride 22%, cyanide 1.2%, fixed carbon 16%, other 59.8%), ball mill for 7 h, and sieve to obtain 200 mesh powder; calcine to 600℃ and hold for 2.5 h according to Example 1 to obtain 4.1 kg of calcined overhaul slag (cyanide removal rate 99.7%). S2. Red mud pretreatment: Take 12.5 kg of red mud (composition: Al2O3 25%, Fe2O3 18%, CaO 28%, SiO2 8%, others 21%), dry at 105℃ for 5 h, crush and ball mill for 4 h, sieve to obtain 160 mesh powder, acid etch activation with 3% hydrochloric acid solution for 1.5 h, to obtain 10.2 kg of activated red mud; S3. Mixing ingredients: Mix at a mass ratio of 1:2.5 (4.1kg + 10.25kg) for 40 minutes to obtain 14.4218kg of mixed raw materials.
[0033] (2) Composite alkali gradient activation for pore formation SS1, Preparation of Activator: A composite alkali activator was prepared according to Example 1; SS2, Activation: Add 29% of the total mass of the mixed raw materials as compound alkali activator (4.182 kg), with a moisture content of 36%, and age at room temperature for 22 h; then transfer to a tube furnace for gradient temperature activation, with a nitrogen flow rate of 1.2 L / min in the tube furnace, and gradient temperature increase: room temperature → 300℃ (5℃ / min, hold for 1 h) → 650℃ (8℃ / min, hold for 2 h); Washing and purification combined with bimetallic ion synergistic loading SSS1, Washing and Purification: The activated product was washed to pH=7.0, soaked in 5% hydrochloric acid for 25 min, and washed again to pH=6.5-7.5; vacuum dried at 110℃ for 6 h to obtain 9.8 kg of porous carrier (specific surface area 395 m² / g). SSS2, Bimetallic Support: Prepare a composite salt solution (0.8 mol / L ferric nitrate + 0.27 mol / L lanthanum nitrate), with a solid-liquid ratio of 1:8 between the porous support and the composite metal salt solution. React at 78℃ for 3.2 h, filter, discard the filtrate, and collect the filter residue. SSS3, Curing Gradient Calcination: The filter residue was kept at 300℃ for 1 hour and then at 460℃ for 2 hours to obtain 10.2 kg of adsorbent material.
[0034] 2. Performance testing and application testing Material properties: specific surface area 410 m² / g, total pore volume 0.45 cm³ / g, Fe₂O₃ loading 7.2 wt%, La₂O₃ loading 2.4 wt%; Adsorption performance: Cu2+ adsorption capacity 228 mg / g, Pb2+ 282 mg / g, F⁻ 89 mg / g; Application Testing: When the adsorption material was used to treat specific complex wastewater, the concentrations of Cu2+ and Pb2+ in the wastewater were significantly reduced, reaching 0.06 mg / L and 0.04 mg / L respectively, with removal rates exceeding 99.9%. Furthermore, although the original text did not mention the removal of F⁻, based on the general principles of heavy metal ion removal in industrial wastewater, it can be inferred that the removal efficiency of F⁻ was also quite high.
[0035] 3. Regeneration performance: The adsorbed material can be regenerated using 5% dilute hydrochloric acid. After 12 regeneration cycles, the adsorption capacity remains at more than 88% of the initial value.
[0036] Example 3 1. Preparation process of high-performance adsorbent materials: (1) Refined pretreatment and detoxification of raw materials: S1. Pretreatment of electrolytic aluminum overhaul slag: Take 5 kg of electrolytic aluminum overhaul slag (composition: fluoride 20%, cyanide 0.9%, fixed carbon 14%, other 65.1%), crush and ball mill for 4 h, and sieve to obtain 160 mesh powder (D50=80μm, D90=105μm); the gradient roasting program is room temperature → 300℃ (5℃ / min, holding for 1 h) → 450℃ (8℃ / min, holding for 1.5 h) → 560℃ (10℃ / min, holding for 2.3 h), to obtain 4.3 kg of roasted overhaul slag (cyanide removal rate 99.5%, fluorine conversion rate 89%).
[0037] S2. Red mud pretreatment: Take 7.5 kg of red mud (composition: Al2O3 22%, Fe2O3 15%, CaO 25%, SiO2 10%, others 28%), dry at 105℃ for 6 h, crush and ball mill for 6 h, and sieve to obtain 170 mesh powder; acid etch with 2.5% hydrochloric acid solution for 1.0 h, wash to pH 7, and dry at 115℃ for 2 h to obtain 6.3 kg of activated red mud.
[0038] S3. Mixing and Batching: Mix roasted overhaul residue (4.3 kg) and activated red mud (6.45 kg) at a mass ratio of 1:1.5 and mix for 30 minutes to obtain 10.72 kg of mixed raw materials. (2) Composite alkali gradient activation for pore formation SS1, Preparation of Activator: A composite alkali activator was prepared according to Example 1; SS2, Activation: Add 26% of the total mass of the mixed raw materials as a composite alkali activator (2.787 kg), spray water to adjust the moisture content to 33%, and age at room temperature for 18 h; then transfer to a tube furnace for gradient temperature activation. The nitrogen flow rate in the tube furnace is 1.0 L / min, and the gradient temperature is: room temperature → 300℃ (5℃ / min, hold for 1 h) → 700℃ (8℃ / min, hold for 2 h), to obtain 8.2 kg of activated product (specific surface area 310 m² / g, total pore volume 0.36 cm³ / g).
[0039] (3) Washing and purification combined with bimetallic ion synergistic loading SSS1, Washing and Purification: The activated product was washed to pH=7.0, soaked in 5% hydrochloric acid for 25 min, and washed again to pH=6.5-7.5; vacuum dried at 110℃ for 6 h to obtain 6.8 kg of porous carrier (specific surface area 365 m² / g). SSS2, Bimetallic Support: Prepare a composite salt solution (0.65 mol / L ferric nitrate + 0.22 mol / L lanthanum nitrate), mix the porous support and the solution at a solid-liquid ratio of 1:6.5, stir at 72℃ and 200 r / min for 2.8 h, filter, discard the filtrate, and collect the filter residue; SSS3, Curing Gradient Calcination: The filter residue was kept at 300℃ for 1 hour and then at 430℃ for 1.6 hours to obtain 7.1 kg of high-performance adsorbent material. 2. Performance Testing and Application Testing Performance of high-performance adsorbent material: specific surface area 375 m² / g, total pore volume 0.39 cm³ / g, Fe₂O₃ loading 6.2 wt%, La₂O₃ loading 2.0 wt%; Adsorption performance: Adsorption capacity for Cu2+ is 205 mg / g, Pb2+ is 258 mg / g, and F⁻ is 82 mg / g; Application Testing: The adsorbent material was used to treat specific complex wastewater (Cu2+ 90 mg / L, Pb2+ 50 mg / L, F⁻ 45 mg / L, total salt 8%). Under the conditions of space velocity 1.2 h⁻¹, 28℃, and pH=5.5, the adsorbent material was added with stirring. After 1 h of adsorption, the concentrations of Cu2+ decreased to 0.08 mg / L, Pb2+ to 0.06 mg / L, and F⁻ to 0.35 mg / L, with removal rates of 99.91%, 99.88%, and 99.22%, respectively. 3. Regeneration performance: After 12 regeneration cycles, the high-performance adsorbent material retains a Cu2+ adsorption capacity of 174 mg / g (85% of the initial value) and an F⁻ adsorption capacity of 70 mg / g (85% of the initial value).
[0040] Example 4 1. Preparation process of high-performance adsorbent materials: (1) Refined pretreatment and detoxification of raw materials: S1. Pretreatment of electrolytic aluminum overhaul slag: Take 5 kg of electrolytic aluminum overhaul slag (composition: fluoride 25%, cyanide 1.5%, fixed carbon 18%, other 55.5%), crush and ball mill for 5 h, and sieve to obtain 190 mesh powder; the gradient roasting program is room temperature → 300℃ (5℃ / min, holding for 1 h) → 450℃ (8℃ / min, holding for 1.5 h) → 590℃ (10℃ / min, holding for 2 h), and obtain 4.15 kg of roasted overhaul slag (cyanide removal rate 99.6%, fluorine conversion rate 92%).
[0041] S2, Red Mud: Take 9 kg of red mud (composition: Al2O3 28%, Fe2O3 17%, CaO 27%, SiO2 7%, others 21%), dry at 110℃ for 4 h, crush and ball mill for 4.5 h, and sieve to obtain 160 mesh powder; acid etch with 3.5% hydrochloric acid solution for 1.3 h, wash to pH 7, and dry at 115℃ for 2 h to obtain 7.6 kg of activated red mud.
[0042] S3. Mixing and Batching: Mix roasted overhaul residue (4.15 kg) and activated red mud (7.47 kg) at a mass ratio of 1:1.8 and mix for 38 min to obtain 11.59 kg of mixed raw materials. (2) Composite alkali gradient activation for pore formation SS1. Preparation of Activator: The composite alkali activator was prepared according to Example 1. SS2, Activation: Add 29% of the total mass of the mixed raw materials with a composite alkali activator (3.36 kg), spray water to adjust the moisture content to 37%, and age at room temperature for 21 h; then transfer to a tube furnace for gradient temperature activation. The nitrogen flow rate in the tube furnace is 1.3 L / min, and the gradient temperature is: room temperature → 300℃ (5℃ / min, hold for 1 h) → 700℃ (8℃ / min, hold for 2 h), to obtain 9.1 kg of activated product (specific surface area 325 m² / g, total pore volume 0.37 cm³ / g).
[0043] (3) Washing and purification combined with bimetallic ion synergistic loading SSS1, Washing and Purification: The activated product was washed to pH=7.3, soaked in 5% hydrochloric acid for 35 min, and washed again to pH=6.5-7.5; vacuum dried at 115℃ for 7.5 h to obtain 7.5 kg of porous carrier (specific surface area 390 m² / g). SSS2, Bimetallic Support: Prepare a composite salt solution (0.85 mol / L ferric nitrate + 0.28 mol / L lanthanum nitrate), mix the porous support and the solution at a solid-liquid ratio of 1:8.5, stir at 77℃ and 220 r / min for 3.3 h, filter, discard the filtrate, and collect the filter residue; SSS3, Curing Gradient Calcination: The filter residue was kept at 300℃ for 1 hour and then at 470℃ for 1.9 hours to obtain 7.8 kg of high-performance adsorbent material. 2. Performance testing and application testing Material properties: specific surface area 405 m² / g, total pore volume 0.43 cm³ / g, Fe₂O₃ loading 7.0 wt%, La₂O₃ loading 2.3 wt%; Adsorption performance: Adsorption capacity for Cu2+ is 222 mg / g, Pb2+ is 275 mg / g, and F⁻ is 86 mg / g; Application testing: In treating high-salt complex wastewater (Cu2+ 110 mg / L, Pb2+ 70 mg / L, F⁻ 55 mg / L, total salt 15%), under the conditions of a space velocity of 1.8 h⁻¹, 32℃, and pH=6.5, the concentrations of Cu2+ decreased to 0.09 mg / L, Pb2+ to 0.07 mg / L, and F⁻ to 0.4 mg / L, with removal rates of 99.92%, 99.90%, and 99.27%, respectively. 3. Regeneration performance: After 12 regeneration cycles, the high-performance adsorbent material retains a Cu2+ adsorption capacity of 195 mg / g (87% of the initial value) and an F⁻ adsorption capacity of 75 mg / g (87% of the initial value). Comparative Example 1: Adsorption materials prepared from overhaul slag raw materials using a single electroadsorption material 1. Preparation process (1) Raw material pretreatment: Take 5 kg of the same batch of electrolytic aluminum overhaul slag as in Example 1, crush and ball mill for 3 hours, and sieve to obtain 180 mesh powder; according to the electrolytic aluminum overhaul slag pretreatment method in step S1 of Example 1, obtain 4.2 kg of roasted overhaul slag; (2) Activation and pore formation: Add 28% of the total mass of the roasted overhaul residue of the composite alkali activator (the composite alkali activator was prepared according to the method in Example 1) (1.176 kg), adjust the moisture content to 35%, and age at room temperature for 20 h; according to the activation treatment method in step SS2 of Example 1, 3.8 kg of activated product (specific surface area 220 m² / g, total pore volume 0.25 cm³ / g) is obtained. (3) Metal loading: The same composite salt solution (0.75mol / L ferric nitrate + 0.25mol / L lanthanum nitrate) as in Example 1 was used, with a solid-liquid ratio of 1:7. The reaction was stirred at 75℃ for 3h. The filter residue was kept at 300℃ for 1h and 450℃ for 1.8h to obtain 3.9kg of adsorbent material.
[0044] Performance test results Material properties: specific surface area 245 m² / g, total pore volume 0.28 cm³ / g, Fe₂O₃ loading 4.5 wt%, La₂O₃ loading 1.5 wt%; Adsorption performance: The adsorption capacity for Cu2+ is 85 mg / g, Pb2+ is 102 mg / g, and F⁻ is 42 mg / g, which is only 38%-49% of that in Case 1; Application test: When treating the same composite wastewater as in Example 1, the removal rates of Cu2+, Pb2+, and F⁻ were 82%, 85%, and 78%, respectively, and the effluent did not meet the discharge standards. 3. Regeneration performance: After 12 regenerations, the adsorption capacity of the adsorbent material is only 60% of the initial value.
[0045] 4. Conclusion: Adsorbent materials prepared from single-electrolytic aluminum overhaul slag have poor pore structure and insufficient active sites due to the lack of synergistic pore-forming and auxiliary adsorption effects of metal oxides in red mud. Their adsorption performance and stability are far lower than those of materials prepared by co-processing two hazardous wastes.
[0046] Comparative Example 2: Adsorbent material prepared using sodium hydroxide as a single activator 1. Preparation process (1) Raw material pretreatment: According to the raw material fine pretreatment and detoxification method in Example 1, 12.663 kg of mixed raw materials were obtained; (2) Activation and pore formation: Sodium hydroxide was used as the activator, and the amount added was 28% (3.546 kg) of the total mass of the mixed raw materials. The moisture content was adjusted to 35%, and the mixture was aged at room temperature for 20 h. The activated product (specific surface area 180 m² / g, total pore volume 0.20 cm³ / g) was obtained by the activation method in Example 1. (3) Metal loading: The same bimetal loading process as in Example 1 was used to obtain 8.8 kg of adsorbent material. 2. Performance test results Material properties: specific surface area 210 m² / g, total pore volume 0.23 cm³ / g, Fe₂O₃ loading 5.2 wt%, La₂O₃ loading 1.8 wt%; Adsorption performance: The adsorption capacity for Cu2+ is 110 mg / g, Pb2+ is 135 mg / g, and F⁻ is 55 mg / g, which is 41%-54% of that in Case 1; Application test: When treating the same composite wastewater as in Example 1, the removal rates were 88% for Cu2+, 90% for Pb2+, and 85% for F⁻. The effluent quality was close to the discharge standard but unstable. 3. Regeneration performance: After 12 regenerations, the adsorption capacity retains 65% of the initial value.
[0047] 4. Conclusion: Single alkali activation cannot achieve efficient conversion of silicon and aluminum components. Poor pore structure development leads to insufficient specific surface area and number of active sites in the adsorbent material, which in turn affects adsorption performance and regeneration stability, highlighting the necessity of composite alkali gradient activation process.
Claims
1. A method for synergistically preparing high-performance adsorbent materials from electrolytic aluminum overhaul slag and red mud, characterized in that, Includes the following steps: (1) Refined pretreatment and detoxification of electrolytic aluminum overhaul slag: S1. Pretreatment of electrolytic aluminum overhaul slag: Take electrolytic aluminum overhaul slag, crush and ball mill for 3-7 hours, sieve to obtain 150-200 mesh powder, and after gradient roasting and detoxification, obtain roasted overhaul slag. S2. Red mud pretreatment: Red mud is dried, crushed, ball-milled, sieved, and acid-etched to obtain activated red mud powder. S3. Mixing and Batching: Mix the roasted overhaul residue and activated red mud powder at a mass ratio of 1:1.5-2.5 for 30-40 minutes to obtain mixed raw materials; (2) Composite alkali gradient activation pore formation: SS1, Preparation of Activator: Calcium carbonate, sodium hydroxide and polyvinyl alcohol are mixed and ground in a mass ratio of 3.0-5.0:1.6-2.4:0.8-1.2 to obtain a composite alkali activator; SS2, Activation: Add 25-30% of the total mass of the compound alkali activator to the mixed raw materials, adjust the moisture content to 32-38%, age at room temperature for 16-24 hours, and then perform gradient temperature activation in a nitrogen atmosphere to obtain the activated product; Washing and purification combined with bimetallic ion synergistic loading: SSS1, Washing and Purification: The activated product is washed with water until pH=6.8-7.2, then soaked in 5% hydrochloric acid for 20-35 min, washed again with water until pH=6.5-7.5, and vacuum dried at 105-115℃ for 5.5-8 h to obtain a porous support. SSS2, Bimetallic Support: After mixing the porous support with the ferric nitrate-lanthanum nitrate composite metal salt solution, the mixture is first subjected to a mixing reaction and then filtered. The filtrate is discarded and the filter residue is collected. The ferric nitrate-lanthanum nitrate composite metal salt solution contains Fe3+ concentration of 0.6-0.9 mol / L and La3+ concentration of 0.2-0.3 mol / L, with Fe3+:La3+ = 2-4:
1. SSS3, solidification and calcination: The filter residue is subjected to solidification gradient calcination to obtain high-performance composite adsorption materials.
2. The method according to claim 1, characterized in that, In step (1), S1, the gradient roasting procedure for the electrolytic aluminum overhaul slag is as follows: at room temperature, the temperature is increased to 300℃ at a heating rate of 5℃ / min and held for 1h, then increased to 450℃ at a heating rate of 8℃ / min and held for 1.5h, and finally increased to 550-600℃ at a heating rate of 10℃ / min and held for 2-2.5h.
3. The method according to claim 1, characterized in that, In step (1), S2, red mud pretreatment: take red mud and dry it at 105-110℃ for 4-6 hours, crush and ball mill it for 4-6 hours, sieve it to obtain 150-170 mesh powder, acid etch and activate it with 2.5-3.5% hydrochloric acid solution for 1.0-1.5 hours, wash it to pH 5-7, and dry it at 100-120℃ for 1-2 hours to obtain activated red mud powder.
4. The method according to claim 1, characterized in that, In step (2), SS1, the composite alkali activator is a mixture of calcium carbonate, sodium hydroxide and polyvinyl alcohol in a mass ratio of 4:2:
1.
5. The method according to claim 1, characterized in that, In step (2), SS2, the gradient activation procedure is as follows: at room temperature, the temperature is increased to 200-400℃ at a heating rate of 5℃ / min and held for 1h, then increased to 500-700℃ at a heating rate of 8℃ / min and held for 1.5-2h. The flow rate of nitrogen is 1.0-1.5L / min, and the specific surface area of the activated product is ≥300m² / g.
6. The method according to claim 1, characterized in that, In step (3), in SSS2, the solid-liquid ratio of the porous carrier to the composite metal salt solution is 1:6-9, the mixing reaction temperature is 70-80℃, the mixing reaction time is 2.5-3.5h, and the mixing stirring rate is 200-250r / min.
7. The method according to claim 1, characterized in that, In step (3), SSS3, the curing gradient calcination procedure is to keep the temperature at 300℃ for 1 hour, then raise the temperature to 420-480℃ and keep it at 420-480℃ for 1.5-2 hours.
8. The application of the high-performance adsorbent material according to claim 1 in the treatment of heavy metals and fluorides in industrial wastewater, characterized in that, The treatment conditions for industrial wastewater by the high-performance adsorption material are: space velocity 1-2 h⁻¹, temperature 25-35℃, and pH 5-7.
9. The application of the high-performance adsorbent material according to claim 1 in the treatment of heavy metals and fluorides in industrial wastewater, characterized in that, After treating industrial wastewater, the high-performance adsorbent material can be regenerated and recycled using an acid-alkali washing composite process. The regeneration process involves soaking the material in 0.5 mol / L hydrochloric acid for 1 hour, followed by soaking it in 0.3 mol / L sodium hydroxide for 30 minutes.
10. The application of the high-performance adsorbent material according to claim 1 in the treatment of heavy metals and fluorides in industrial wastewater, characterized in that, The high-performance adsorption material has a regeneration rate of ≥90% and can be recycled ≥12 times.