Activation of palygorskite by acid solution, preparation method thereof and application of the activated palygorskite in heavy metal adsorption
By activating attapulgite with acid solution and loading it with magnetic nanoparticles, an ordered mesoporous channel is constructed, which solves the problems of low adsorption capacity and difficult separation of attapulgite, and realizes efficient heavy metal adsorption and magnetic recovery, which is suitable for heavy metal wastewater treatment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INNER MONGOLIA SAIDE TECHNOLOGY CO LTD
- Filing Date
- 2026-04-17
- Publication Date
- 2026-05-29
Abstract
Description
Technical Field
[0001] This invention relates to the field of attapulgite processing technology, specifically to an acid-activated attapulgite, its preparation method, and its application in heavy metal adsorption. Background Technology
[0002] Attapulgite is a natural one-dimensional nano-chain layered silicate clay mineral with a certain adsorption capacity due to its large specific surface area and rich silanol content. However, natural attapulgite suffers from drawbacks such as easy pore clogging and limited active sites, resulting in generally low adsorption capacity, which is insufficient to meet the requirements of practical wastewater treatment. Acid activation is a commonly used modification method to improve its performance. By dissolving some octahedral cations, it can unblock pores, increase specific surface area and surface acidic sites, thereby enhancing its adsorption capacity for heavy metal ions. However, acid-activated attapulgite is usually a fine powder, which presents problems such as difficulty in solid-liquid separation, low recovery rate, and easy secondary pollution in practical water treatment applications, severely limiting its large-scale application. Summary of the Invention
[0003] To address the shortcomings of existing technologies, this invention provides an acid-activated attapulgite, its preparation method, and its application in heavy metal adsorption. The prepared magnetic acid-activated attapulgite possesses both high adsorption capacity and excellent magnetic separation ability, making it a high-performance, easily recyclable, and promising heavy metal wastewater treatment adsorption material.
[0004] A method for preparing acid-activated attapulgite includes the following steps: (1) Mix the attapulgite raw material with an inorganic acid solution for acid treatment, separate the solid and liquid and wash until neutral to obtain acid-activated attapulgite; (2) The acid-activated attapulgite soil is mixed with a water-soluble organic template agent and aged to form a precursor; (3) In an air atmosphere, the precursor is mixed with a solution containing ferrous salts and ferric salts and an antioxidant, and the pH is adjusted to carry out a co-precipitation reaction so that the magnetic nanoparticles are loaded onto the surface of the material. (4) Calcination of coprecipitated products simultaneously achieves template removal, magnetic particle crystallization and pore structure stabilization.
[0005] Preferably, in step (1), the inorganic acid solution is hydrochloric acid with a concentration of 1.5–5.0 mol / L; the acid treatment temperature is 70–100℃ and the treatment time is 1–5 hours.
[0006] Preferably, in step (2), the water-soluble organic template agent is selected from at least one of polyethylene glycol, soluble starch, and polyvinyl alcohol with a molecular weight of 4000–8000.
[0007] Preferably, in step (2), the mass ratio of the water-soluble organic template agent to the acid-activated attapulgite is (3–20):100; the aging temperature is 45–70℃; and the aging time is 3.5–7 hours.
[0008] Preferably, in step (3), the molar ratio of the divalent ferric salt to the trivalent ferric salt is 1:(1.5–2.5); the antioxidant is selected from at least one of ascorbic acid, citric acid, glucose, and gallic acid.
[0009] Preferably, in step (3), the amount of antioxidant added is 0.3%–3.0% of the total mass of iron salt; the pH of the coprecipitation reaction is 9.0–11.0, the reaction temperature is 60–80℃, and the reaction time is 0.8–2.0 hours.
[0010] Preferably, in step (3), the coprecipitation reaction is carried out under stirring conditions at a stirring rate of 300–1000 rpm.
[0011] Preferably, in step (4), the calcination temperature is 350–500℃, the calcination time is 1.5–4 hours, and the heating rate is 2–8℃ / min.
[0012] This invention provides an acid-activated attapulgite prepared by the above-described method for preparing acid-activated attapulgite.
[0013] This invention provides an application of attapulgite in heavy metal adsorption, wherein the attapulgite is dispersed in water containing heavy metal ions to adsorb the heavy metal ions, and then the attapulgite is separated from the water by an external magnetic field.
[0014] This invention provides a method for preparing acid-activated attapulgite. Through acid activation and template agent modification, the specific surface area of attapulgite is significantly increased, and an ordered, interconnected mesoporous channel is constructed, exposing more adsorption sites such as surface-active silanol groups. It exhibits excellent adsorption performance for various heavy metal ions. Furthermore, through co-precipitation reaction under optimized conditions, well-crystallized and uniformly distributed magnetic iron nanoparticles are selectively loaded onto the surface of the pre-constructed porous attapulgite structure. This allows the resulting material to achieve rapid and thorough solid-liquid separation under an external magnetic field, with a high magnetic recovery rate. This fundamentally solves the problems of difficult separation and easy loss of traditional powder adsorbents, reducing operating costs and the risk of secondary pollution. Detailed Implementation
[0015] This invention provides a method for preparing acid-activated attapulgite, comprising the following steps: (1) Mix the attapulgite raw material with an inorganic acid solution for acid treatment, separate the solid and liquid and wash until neutral to obtain acid-activated attapulgite; (2) Acid-activated attapulgite is mixed with water-soluble organic template agent and aged to form a precursor; (3) In an air atmosphere, the precursor is mixed with a solution containing ferrous salts and ferric salts and an antioxidant, and the pH is adjusted to carry out a co-precipitation reaction so that the magnetic nanoparticles are loaded onto the surface of the material. (4) Calcination of coprecipitated products simultaneously achieves template removal, magnetic particle crystallization and pore structure stabilization.
[0016] In step (1), the inorganic acid solution is hydrochloric acid with a concentration of 1.5–5.0 mol / L; the acid treatment temperature is 70–100℃ and the treatment time is 1–5 hours.
[0017] In step (2), the water-soluble organic template agent is selected from at least one of polyethylene glycol, soluble starch, and polyvinyl alcohol with a molecular weight of 4000–8000.
[0018] In step (2), the mass ratio of water-soluble organic template agent to acid-activated attapulgite is (3–20):100; the aging temperature is 45–70℃ and the aging time is 3.5–7 hours.
[0019] In step (3), the molar ratio of ferrous salt to ferric salt is 1:(1.5–2.5); the antioxidant is selected from at least one of ascorbic acid, citric acid, glucose, and gallic acid.
[0020] In step (3), the amount of antioxidant added is 0.3%–3.0% of the total mass of iron salt; the pH of the coprecipitation reaction is 9.0–11.0, the reaction temperature is 60–80℃, and the reaction time is 0.8–2.0 hours.
[0021] In step (3), the coprecipitation reaction is carried out under stirring conditions at a stirring rate of 300–1000 rpm.
[0022] In step (4), the calcination temperature is 350–500℃, the calcination time is 1.5–4 hours, and the heating rate is 2–8℃ / min.
[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.
[0024] Example 1-1: A method for preparing acid-activated attapulgite includes the following steps: (1) Take 100g of raw attapulgite soil and mix it with 500mL of 1.5mol / L hydrochloric acid solution. Stir and react at 70℃ for 5 hours. After the reaction is completed, perform solid-liquid separation and wash the solid product repeatedly with deionized water until the pH of the filtrate is neutral to obtain acid-activated attapulgite soil. Dry it at 105℃ for later use.
[0025] (2) Take 10g of acid-activated attapulgite obtained in step (1), mix it with 0.6g of polyethylene glycol-6000 and 30mL of deionized water, and age it at 45℃ for 7 hours to obtain precursor slurry.
[0026] (3) Preparation of iron salt solution: Dissolve 2.78 g of FeSO4·7H2O and 6.06 g of FeCl3·6H2O in 50 mL of deionized water, with a molar ratio of ferrous salt to ferric salt of 1:1.5. Add 0.027 g of citric acid as an antioxidant (approximately 0.3% of the total mass of iron salt). Slowly add the previously prepared slurry to the above iron salt solution while stirring at 550 rpm, and mix thoroughly. Adjust the pH of the system to 9.0 with 1 mol / L NaOH solution, and continue stirring at 60 °C for 2.0 hours to carry out co-precipitation.
[0027] (4) After filtering, washing and drying the coprecipitated product, place it in a muffle furnace and heat it to 350°C at a rate of 2°C / min, and calcine it at this temperature for 4 hours. After natural cooling, grind it to obtain the magnetic acid activated attapulgite product M-ATP-1.
[0028] Examples 1-2 (1) Take 100g of raw attapulgite soil and mix it with 500mL of 1.5mol / L hydrochloric acid solution. Stir and react at 70℃ for 5 hours. After the reaction is completed, perform solid-liquid separation and wash the solid product repeatedly with deionized water until the pH of the filtrate is neutral to obtain acid-activated attapulgite soil. Dry it at 105℃ for later use.
[0029] (2) Take 10g of acid-activated attapulgite obtained in step (1), mix it with 0.6g of polyethylene glycol-6000 and 30mL of deionized water, and age it at 45℃ for 7 hours to obtain precursor slurry.
[0030] (3) Preparation of iron salt solution: Dissolve 3.70 g of FeSO4·7H2O and 6.06 g of FeCl3·6H2O in 50 mL of deionized water, with a molar ratio of ferrous salt to ferric salt of 1:2.0. Add 0.027 g of citric acid as an antioxidant (approximately 0.3% of the total mass of iron salt). Slowly add the previously prepared slurry to the above iron salt solution while stirring at 550 rpm, and mix thoroughly. Adjust the pH of the system to 9.0 with 1 mol / L NaOH solution, and continue stirring at 60 °C for 2.0 hours to carry out co-precipitation.
[0031] (4) After filtering, washing and drying the coprecipitated product, place it in a muffle furnace and heat it to 350°C at a rate of 2°C / min, and calcine it at this temperature for 4 hours. After natural cooling, grind it to obtain the magnetic acid activated attapulgite product M-ATP-2.
[0032] Examples 1-3 (1) Take 100g of raw attapulgite soil and mix it with 500mL of 1.5mol / L hydrochloric acid solution. Stir and react at 70℃ for 5 hours. After the reaction is completed, perform solid-liquid separation and wash the solid product repeatedly with deionized water until the pH of the filtrate is neutral to obtain acid-activated attapulgite soil. Dry it at 105℃ for later use.
[0033] (2) Take 10g of acid-activated attapulgite obtained in step (1), mix it with 0.6g of polyethylene glycol-6000 and 30mL of deionized water, and age it at 45℃ for 7 hours to obtain precursor slurry.
[0034] (3) Preparation of iron salt solution: Dissolve 4.17g of FeSO4·7H2O and 5.41g of FeCl3·6H2O in 50mL of deionized water, with a molar ratio of ferrous salt to ferric salt of 1:2.5. Add 0.027g of citric acid as an antioxidant (approximately 0.3% of the total mass of iron salt). Slowly add the previously prepared slurry to the above iron salt solution while stirring at 550rpm, and mix thoroughly. Adjust the pH of the system to 9.0 with 1mol / L NaOH solution, and continue stirring at 60℃ for 2.0 hours to carry out co-precipitation.
[0035] (4) After filtering, washing and drying the coprecipitated product, place it in a muffle furnace and heat it to 350°C at a rate of 2°C / min, and calcine it at this temperature for 4 hours. After natural cooling, grind it to obtain the magnetic acid activated attapulgite product M-ATP-3.
[0036] Example 2-1 A method for preparing acid-activated attapulgite includes the following steps: (1) Take 100g of attapulgite soil and mix it with 400mL of 3.0mol / L hydrochloric acid solution. Stir and react at 85℃ for 3 hours. The subsequent washing and drying are the same as in Example 1-1.
[0037] (2) Take 10g of acid-activated attapulgite, mix it with 1.0g of soluble starch and 40mL of deionized water, and age it at 60℃ for 4 hours to obtain the precursor slurry.
[0038] (3) Preparation of iron salt solution: The molar ratio of ferrous iron to ferric iron was fixed at 1:2.0 (same as in Examples 1-2). 3.70 g of FeSO4·7H2O and 6.06 g of FeCl3·6H2O were dissolved in 50 mL of deionized water. 0.088 g of citric acid was added as an antioxidant (the amount added was approximately 1.0% of the total mass of the iron salt). The precursor slurry was added to the iron salt solution while stirring at 600 rpm. The pH was adjusted to 10.0 with NaOH solution, and the reaction was stirred at 70 °C for 1.5 hours.
[0039] (4) After filtering, washing and drying the product, the temperature was increased to 400℃ at 5℃ / min and calcined for 2.5 hours. The product was labeled as M-ATP-4.
[0040] Example 2-2 A method for preparing acid-activated attapulgite includes the following steps: (1) Take 100g of attapulgite soil and mix it with 400mL of 3.0mol / L hydrochloric acid solution. Stir and react at 85℃ for 3 hours. The subsequent washing and drying are the same as in Example 1-1.
[0041] (2) Take 10g of acid-activated attapulgite, mix it with 1.0g of soluble starch and 40mL of deionized water, and age it at 60℃ for 4 hours to obtain the precursor slurry.
[0042] (3) Preparation of iron salt solution: The molar ratio of ferrous iron to ferric iron was fixed at 1:2.0 (same as in Examples 1-2). 3.70 g of FeSO4·7H2O and 6.06 g of FeCl3·6H2O were dissolved in 50 mL of deionized water. 0.026 g of citric acid was added as an antioxidant (the amount added was approximately 0.3% of the total mass of the iron salt). The precursor slurry was added to the iron salt solution while stirring at 600 rpm. The pH was adjusted to 10.0 with NaOH solution, and the reaction was stirred at 70 °C for 1.5 hours.
[0043] (4) After filtering, washing and drying the product, the temperature was increased to 400℃ at 5℃ / min and calcined for 2.5 hours. The product was labeled as M-ATP-5.
[0044] Example 2-3 A method for preparing acid-activated attapulgite includes the following steps: (1) Take 100g of attapulgite soil and mix it with 400mL of 3.0mol / L hydrochloric acid solution. Stir and react at 85℃ for 3 hours. The subsequent washing and drying are the same as in Example 1-1.
[0045] (2) Take 10g of acid-activated attapulgite, mix it with 1.0g of soluble starch and 40mL of deionized water, and age it at 60℃ for 4 hours to obtain the precursor slurry.
[0046] (3) Preparation of iron salt solution: The molar ratio of ferrous iron to ferric iron was fixed at 1:2.0 (same as in Examples 1-2). 3.70 g of FeSO4·7H2O and 6.06 g of FeCl3·6H2O were dissolved in 50 mL of deionized water. 0.265 g of citric acid was added as an antioxidant (the amount added was approximately 3.0% of the total mass of the iron salt). The precursor slurry was added to the iron salt solution while stirring at 600 rpm. The pH was adjusted to 10.0 with NaOH solution, and the reaction was stirred at 70 °C for 1.5 hours.
[0047] (4) After filtering, washing and drying the product, the temperature was increased to 400℃ at 5℃ / min and calcined for 2.5 hours. The product was labeled as M-ATP-6.
[0048] Comparative Example 1: (1) Take 100g of raw attapulgite soil and mix it with 500mL of 0.5mol / L hydrochloric acid solution. Stir and react at 70℃ for 5 hours. After the reaction is completed, perform solid-liquid separation and wash the solid product repeatedly with deionized water until the pH of the filtrate is neutral to obtain acid-activated attapulgite soil. Dry it at 105℃ for later use.
[0049] (2) Take 10g of acid-activated attapulgite obtained in step (1), mix it with 0.6g of polyethylene glycol-6000 and 30mL of deionized water, and age it at 45℃ for 7 hours to obtain precursor slurry.
[0050] (3) Preparation of iron salt solution: Dissolve 3.70 g of FeSO4·7H2O and 6.06 g of FeCl3·6H2O in 50 mL of deionized water, with a molar ratio of ferrous salt to ferric salt of 1:2.0. Add 0.027 g of citric acid as an antioxidant (approximately 0.3% of the total mass of iron salt). Slowly add the previously prepared slurry to the above iron salt solution while stirring at 550 rpm, and mix thoroughly. Adjust the pH of the system to 9.0 with 1 mol / L NaOH solution, and continue stirring at 60 °C for 2.0 hours to carry out co-precipitation.
[0051] (4) After filtering, washing and drying the coprecipitated product, place it in a muffle furnace and heat it to 350°C at a rate of 2°C / min, and calcine it at this temperature for 4 hours. After natural cooling, grind it to obtain the magnetic acid activated attapulgite product C-ATP-1.
[0052] Comparative Example 2: (1) Take 100g of raw attapulgite soil and mix it with 500mL of 1.5mol / L hydrochloric acid solution. Stir and react at 70℃ for 5 hours. After the reaction is completed, perform solid-liquid separation and wash the solid product repeatedly with deionized water until the pH of the filtrate is neutral to obtain acid-activated attapulgite soil. Dry it at 105℃ for later use.
[0053] (2) Take 10g of acid-activated attapulgite obtained in step (1) and mix it evenly with 30mL of deionized water. Then, age it at 45℃ for 7 hours to obtain the precursor slurry.
[0054] (3) Preparation of iron salt solution: Dissolve 3.70 g of FeSO4·7H2O and 6.06 g of FeCl3·6H2O in 50 mL of deionized water, with a molar ratio of ferrous salt to ferric salt of 1:2.0. Add 0.027 g of citric acid as an antioxidant (approximately 0.3% of the total mass of iron salt). Slowly add the previously prepared slurry to the above iron salt solution while stirring at 550 rpm, and mix thoroughly. Adjust the pH of the system to 9.0 with 1 mol / L NaOH solution, and continue stirring at 60 °C for 2.0 hours to carry out co-precipitation.
[0055] (4) After filtering, washing and drying the coprecipitated product, place it in a muffle furnace and heat it to 350°C at a heating rate of 2°C / min, and calcine it at this temperature for 4 hours. After natural cooling, grind it to obtain the magnetic acid activated attapulgite product C-ATP-2.
[0056] Comparative Example 3: (1) Take 100g of raw attapulgite soil and mix it with 500mL of 1.5mol / L hydrochloric acid solution. Stir and react at 70℃ for 5 hours. After the reaction is completed, perform solid-liquid separation and wash the solid product repeatedly with deionized water until the pH of the filtrate is neutral to obtain acid-activated attapulgite soil. Dry it at 105℃ for later use.
[0057] (2) Take 10g of acid-activated attapulgite obtained in step (1), mix it with 0.6g of sodium dodecyl sulfate (SDS) and 30mL of deionized water, and age it at 45℃ for 7 hours to obtain precursor slurry.
[0058] (3) Preparation of iron salt solution: Dissolve 3.70 g of FeSO4·7H2O and 6.06 g of FeCl3·6H2O in 50 mL of deionized water, with a molar ratio of ferrous salt to ferric salt of 1:2.0. Add 0.027 g of citric acid as an antioxidant (approximately 0.3% of the total mass of iron salt). Slowly add the previously prepared slurry to the above iron salt solution while stirring at 550 rpm, and mix thoroughly. Adjust the pH of the system to 9.0 with 1 mol / L NaOH solution, and continue stirring at 60 °C for 2.0 hours to carry out co-precipitation.
[0059] (4) After filtering, washing and drying the coprecipitated product, place it in a muffle furnace and heat it to 350°C at a rate of 2°C / min, and calcine it at this temperature for 4 hours. After natural cooling, grind it to obtain the magnetic acid activated attapulgite product C-ATP-3.
[0060] Comparative Example 4: (1) Take 100g of raw attapulgite soil and mix it with 500mL of 1.5mol / L hydrochloric acid solution. Stir and react at 70℃ for 5 hours. After the reaction is completed, perform solid-liquid separation and wash the solid product repeatedly with deionized water until the pH of the filtrate is neutral to obtain acid-activated attapulgite soil. Dry it at 105℃ for later use.
[0061] (2) Take 10g of acid-activated attapulgite obtained in step (1), mix it with 0.2g of polyethylene glycol-6000 and 30mL of deionized water, and age it at 45℃ for 7 hours to obtain the precursor slurry.
[0062] (3) Preparation of iron salt solution: Dissolve 3.70 g of FeSO4·7H2O and 6.06 g of FeCl3·6H2O in 50 mL of deionized water, with a molar ratio of ferrous salt to ferric salt of 1:2.0. Add 0.027 g of citric acid as an antioxidant (approximately 0.3% of the total mass of iron salt). Slowly add the previously prepared slurry to the above iron salt solution while stirring at 550 rpm, and mix thoroughly. Adjust the pH of the system to 9.0 with 1 mol / L NaOH solution, and continue stirring at 60 °C for 2.0 hours to carry out co-precipitation.
[0063] (4) After filtering, washing and drying the coprecipitated product, place it in a muffle furnace and heat it to 350°C at a rate of 2°C / min, and calcine it at this temperature for 4 hours. After natural cooling, grind it to obtain the magnetic acid activated attapulgite product C-ATP-4.
[0064] Comparative Example 5: (1) Take 100g of raw attapulgite soil and mix it with 500mL of 1.5mol / L hydrochloric acid solution. Stir and react at 70℃ for 5 hours. After the reaction is completed, perform solid-liquid separation and wash the solid product repeatedly with deionized water until the pH of the filtrate is neutral to obtain acid-activated attapulgite soil. Dry it at 105℃ for later use.
[0065] (2) Take 10g of acid-activated attapulgite obtained in step (1), mix it with 0.6g of polyethylene glycol-6000 and 30mL of deionized water, and age it at 45℃ for 7 hours to obtain precursor slurry.
[0066] (3) Preparation of iron salt solution: Dissolve 3.70 g of FeSO4·7H2O and 6.06 g of FeCl3·6H2O in 50 mL of deionized water, with a molar ratio of ferrous salt to ferric salt of 1:2.0. Add 0.027 g of citric acid as an antioxidant (approximately 0.3% of the total mass of iron salt). Slowly add the previously prepared slurry to the above iron salt solution while stirring at 350 rpm, and mix thoroughly. Adjust the pH of the system to 9.0 with 1 mol / L NaOH solution, and continue stirring at 60 °C for 2.0 hours to carry out co-precipitation.
[0067] (4) After filtering, washing and drying the coprecipitated product, place it in a muffle furnace and heat it to 350°C at a rate of 2°C / min, and calcine it at this temperature for 4 hours. After natural cooling, grind it to obtain the magnetic acid activated attapulgite product C-ATP-5.
[0068] The following performance tests were performed on the products obtained in the above embodiments and comparative examples: 1. Adsorption performance test for multiple heavy metal ions: Solutions of Pb(NO3)2, K2Cr2O7, NiSO4, and CuSO4 with initial concentrations of 100 mg / L were prepared, and 50 mL of each was taken, with the pH adjusted to 5.0. 0.05 g of each sample was added to each solution, and the mixture was incubated at 25℃ with shaking for 4 hours to reach adsorption equilibrium. After filtration, the concentration of each metal ion in the filtrate was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), and the adsorption capacity (mg / g) and adsorption rate (%) were calculated. 2. Magnetic Recovery Rate Test: After the adsorption test, the suspension was allowed to stand. A neodymium iron boron magnet with a surface magnetic field strength of approximately 300 mT was used to attract the magnetic material from the solution for 1 minute. The suspended solids that were not attracted by the magnet were collected, dried, and weighed. Recovery rate (%) = (1 - mass of unrecovered portion / mass of initial sample) × 100%.
[0069] Sample number <![CDATA[Pb 2+ Adsorption capacity (mg / g) / Adsorption rate (%) Cr(VI) adsorption capacity (mg / g) / adsorption rate (%) <![CDATA[Ni 2+ Adsorption capacity (mg / g) / Adsorption rate (%) <![CDATA[Cu 2+ Adsorption capacity (mg / g) / Adsorption rate (%) Magnetic recovery rate (%) M-ATP-1 42.3 / 84.6 35.8 / 71.6 28.5 / 57.0 24.1 / 48.2 92.5 M-ATP-2 48.7 / 97.4 41.2 / 82.4 33.6 / 67.2 29.8 / 59.6 96.8 M-ATP-3 45.1 / 90.2 38.9 / 77.8 30.2 / 60.4 26.5 / 53.0 98.2 M-ATP-4 47.5 / 95.0 40.5 / 81.0 32.8 / 65.6 28.9 / 57.8 95.1 M-ATP-5 44.8 / 89.6 37.2 / 74.4 29.1 / 58.2 25.7 / 51.4 93.7 M-ATP-6 46.9 / 93.8 39.1 / 78.2 31.5 / 63.0 27.6 / 55.2 94 C-ATP-1 35.2 / 70.4 28.9 / 57.8 22.3 / 44.6 19.8 / 39.6 94.5 C-ATP-2 38.9 / 77.8 32.5 / 65.0 26.1 / 52.2 22.4 / 44.8 88.3 C-ATP-3 41.5 / 83.0 34.8 / 69.6 27.9 / 55.8 24.0 / 48.0 90.1 C-ATP-4 43.1 / 86.2 36.1 / 72.2 28.7 / 57.4 25.2 / 50.4 92 C-ATP-5 46.0 / 92.0 37.5 / 75.0 29.8 / 59.6 26.8 / 53.6 91.5 The magnetic acid-activated attapulgite product prepared by the method of this invention exhibits resistance to four typical heavy metal ions (Pb) in aqueous solution. 2+ Cr(VI), Ni 2+ Cu 2+ All exhibited excellent adsorption capacity. The test data clearly showed the order of adsorption capacity and adsorption rate: Pb>Cr>Ni>Cu. This indicates that the material of this invention is not only suitable for the treatment of single lead pollution, but also has significant potential for treating complex wastewater containing multiple heavy metals.
[0070] The example data clearly shows that when Fe 2+ :Fe 3+At a molar ratio of 1:2.0, the material achieves an optimal balance between adsorption performance and magnetic responsiveness. This ratio is most conducive to the formation of high-purity, highly crystalline magnetic Fe3O4 nanoparticles. A ratio that is too low leads to insufficient magnetic particle loading and weakened magnetic recovery; while a ratio that is too high may slightly increase the magnetic response due to the increased total iron loading, excessive ferric salts easily form a non-magnetic ferric hydroxide coating, occupying or shielding some surface-active adsorption sites, resulting in a noticeable decrease in the adsorption capacity for various heavy metals.
[0071] In addition, adding an appropriate amount of 0.3-3.0% citric acid as an antioxidant can effectively prevent Fe 2+ Premature oxidation must be avoided to ensure the formation of the target magnetic phase. Insufficient addition leads to inadequate protection, impairing the magnetic properties and structural order of the product, thus affecting adsorption and recovery. Excessive addition, with its excessive organic ligands, may interfere with the uniformity of the co-precipitation process and the anchoring of particles on the support surface, resulting in slight performance degradation.
[0072] A comparison between Comparative Example 1 and Example 2 shows that insufficient acid activation directly leads to insufficient intrinsic adsorption capacity of the material, resulting in the lowest adsorption capacity among all comparative examples. A comparison between Comparative Examples 2 and 3 and Example 2 demonstrates the role of selecting a suitable template in constructing the adsorption pore structure. Disordered or ineffective pore structures, on the one hand, limit adsorbate diffusion and site utilization, leading to a decrease in adsorption capacity; on the other hand, they prevent magnetic particles from being uniformly and stably loaded at ideal positions, significantly reducing the recovery rate. A comparison between Comparative Example 4 and Example 2 shows that when the amount of template agent is reduced, the pore structure is not fully developed, and the performance is lower than the preferred ratio. A comparison between Comparative Example 5 and Example 2 shows that when the stirring speed decreases, the adsorption capacity of the material for Pb and Cr decreases, and the magnetic recovery rate also decreases.
[0073] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing attapulgite activated with acid solution, characterized in that, Includes the following steps: (1) Mix the attapulgite raw material with an inorganic acid solution for acid treatment, separate the solid and liquid and wash until neutral to obtain acid-activated attapulgite; (2) The acid-activated attapulgite soil is mixed with a water-soluble organic template agent and aged to form a precursor; (3) In an air atmosphere, the precursor is mixed with a solution containing ferrous salts and ferric salts and an antioxidant, and the pH is adjusted to carry out a co-precipitation reaction so that magnetic nanoparticles are loaded onto the surface of the material. (4) Calcination of coprecipitated products simultaneously achieves template removal, magnetic particle crystallization and pore structure stabilization.
2. The method for preparing acid-activated attapulgite as described in claim 1, characterized in that, In step (1), the inorganic acid solution is hydrochloric acid with a concentration of 1.5–5.0 mol / L; the acid treatment temperature is 70–100℃ and the treatment time is 1–5 hours.
3. The method for preparing acid-activated attapulgite as described in claim 1, characterized in that, In step (2), the water-soluble organic template agent is selected from at least one of polyethylene glycol, soluble starch, and polyvinyl alcohol with a molecular weight of 4000–8000.
4. The method for preparing acid-activated attapulgite as described in claim 1 or 3, characterized in that, In step (2), the mass ratio of the water-soluble organic template agent to the acid-activated attapulgite is (3–20):100; the aging temperature is 45–70℃, and the aging time is 3.5–7 hours.
5. The method for preparing acid-activated attapulgite as described in claim 1, characterized in that, In step (3), the molar ratio of the ferrous salt to the ferric salt is 1:(1.5–2.5); the antioxidant is selected from at least one of ascorbic acid, citric acid, glucose, and gallic acid.
6. A method for preparing acid-activated attapulgite as described in claim 1 or 5, characterized in that, In step (3), the amount of antioxidant added is 0.3%–3.0% of the total mass of iron salt; the pH of the coprecipitation reaction is 9.0–11.0, the reaction temperature is 60–80℃, and the reaction time is 0.8–2.0 hours.
7. The method for preparing acid-activated attapulgite as described in claim 1, characterized in that, In step (3), the coprecipitation reaction is carried out under stirring conditions at a stirring rate of 300–1000 rpm.
8. The method for preparing acid-activated attapulgite as described in claim 1, characterized in that, In step (4), the calcination temperature is 350–500℃, the calcination time is 1.5–4 hours, and the heating rate is 2–8℃ / min.
9. Acid-activated attapulgite prepared by a method for preparing acid-activated attapulgite according to any one of claims 1-8.
10. The application of attapulgite in heavy metal adsorption as described in claim 9, characterized in that, The attapulgite clay is dispersed in water containing heavy metal ions to adsorb the heavy metal ions, and then the attapulgite clay is separated from the water by an external magnetic field.