Preparation method of acid-salt activated attapulgite and application of acid-salt activated attapulgite in ammonia-nitrogen wastewater treatment

Abstract

The invention relates to the technical field of attapulgite, and provides a preparation method of acid-salt activated attapulgite and application of the acid-salt activated attapulgite in ammonia-nitrogen wastewater treatment.The preparation method of the acid-salt activated attapulgite comprises the following steps that 1, a titanium salt solution, a magnesium salt solution and acid-activated attapulgite slurry are prepared; 2, synchronously adding a titanium salt solution and a magnesium salt solution into the acid-activated attapulgite slurry, and uniformly dispersing to obtain a titanium salt-magnesium salt-attapulgite mixed slurry; wherein the solid-to-liquid ratio of the attapulgite in the mixed slurry of the titanium salt, the magnesium salt and the attapulgite is (1: 8)-(1: 12), 0.03-0.06 mol of the titanium salt is correspondingly added into every 100g of the acid-activated attapulgite, and the molar ratio of the titanium salt to the magnesium salt is (1: 1.5)-(1: 2.5); 3, dropwise adding a 1-2 mol / L NaOH solution into the titanium salt-magnesium salt-attapulgite mixed slurry prepared in the step 2 while stirring, and adjusting the pH value to 9-10 to obtain a loaded and settled mixed slurry; 4, transferring the loaded and settled mixed slurry obtained in the step 3 to 60 DEG C, standing and aging for 4-6 hours; and 5, cooling, centrifuging, resuspending and washing, centrifuging, drying and grinding the loaded and settled mixed slurry obtained after the reaction in the step 4 to obtain a finished product.

Description

Technical Field

[0001] This invention relates to the field of attapulgite technology, specifically to a method for preparing acid-salt activated attapulgite and its application in ammonia nitrogen wastewater treatment. Background Technology

[0002] With the rapid development of industry and agriculture, the excessive use of chemical fertilizers, the discharge of aquatic wastewater, and the indiscriminate dumping of industrial wastewater have led to serious exceedances of ammonia nitrogen levels in water bodies. Eutrophication not only disrupts the aquatic ecological balance but also threatens human drinking water safety. However, the adsorption of nutrients by natural minerals, such as attapulgite, followed by slow release, can effectively reduce the content of nutrients in water bodies without causing new environmental pollution, thus demonstrating a certain degree of water body treatment effectiveness.

[0003] Existing methods for modifying or activating attapulgite mainly include thermal modification, acid modification, and alkali modification.

[0004] Therefore, we propose a method for preparing acid-salt activated attapulgite and its application in ammonia nitrogen wastewater treatment. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing acid-salt activated attapulgite and its application in ammonia nitrogen wastewater treatment. This method overcomes the deficiencies of existing technologies, has a reasonable design, a compact structure, and solves existing problems.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing acid-salt activated attapulgite, characterized by comprising the following steps:

[0008] 1. Preparation of titanium salt solution, magnesium salt solution and acid-activated attapulgite slurry;

[0009] 2. Add titanium salt solution and magnesium salt solution simultaneously to acid-activated attapulgite slurry and disperse evenly to obtain a mixed slurry of titanium salt-magnesium salt-attapulgite;

[0010] In the mixed slurry of titanium salt, magnesium salt and attapulgite, the solid-liquid ratio of attapulgite is 1:8-1:12, and 0.03mol-0.06mol of titanium salt is added for every 100g of acid-activated attapulgite. The molar ratio of titanium salt to magnesium salt is 1:1.5-1:2.5.

[0011] 3. Add 1-2 mol / L NaOH solution dropwise to the titanium salt-magnesium salt-attapulgite mixed slurry prepared in step 2 above, while stirring, and adjust the pH to 9-10 to obtain a mixed slurry with load settling.

[0012] 4. Transfer the mixed slurry obtained in step 3 to 60℃ and let it stand for aging for 4-6 hours;

[0013] 5. The mixed slurry obtained after the reaction in step 4 is cooled, centrifuged, resuspended and washed, centrifuged again, dried and ground to obtain the finished product.

[0014] Furthermore, the titanium salt is TiOSO4.

[0015] Furthermore, the magnesium salt is MgCl2 or MgSO4.

[0016] Furthermore, for every 100g of acid-activated attapulgite, 0.04-0.05mol of titanium salt is added, and the molar ratio of TiOSO4 to MgCl2 is 1:2.0-1:2.5.

[0017] Furthermore, for every 100g of acid-activated attapulgite, 0.05mol of titanium salt is added, and the molar ratio of TiOSO4 to MgCl2 is 1:2.4.

[0018] Furthermore, in step 2, a low-speed stirring of 300-500 r / min is used for 1 hour, and the temperature is controlled at 60-70℃.

[0019] In step 3, the stirring speed is increased to 600-800 r / min, and the dropping speed is controlled at 2-5 drops / second.

[0020] Furthermore, in step 2, the acid-activated attapulgite is obtained by the following method:

[0021] S1. Add water to attapulgite to prepare a slurry with a mass concentration of 5%-10%. After stirring and dispersing, allow it to settle by gravity. Take the upper layer of slurry, dehydrate and dry it to obtain purified attapulgite.

[0022] S2. Add 2 mol / L-4 mol / L hydrochloric acid or sulfuric acid to the attapulgite purified in step S1, with a solid-liquid ratio of 1:10. Stir at 60-80℃ for 2-4 hours, let stand for 4-8 hours, remove the upper turbid liquid, and retain the bottom precipitate. The bottom precipitate is the acid-activated attapulgite.

[0023] S3. Wash the precipitate obtained in step S2 repeatedly with deionized water, centrifuge, discard the supernatant, and repeat this step until the supernatant pH is 6.5-7.

[0024] S4. Dry the precipitate obtained in step S3 at 105-110℃ and grind it to 200-400 mesh.

[0025] This invention also provides the application of the above-mentioned acid-activated attapulgite in ammonia nitrogen wastewater.

[0026] This invention provides a method for preparing acid-salt activated attapulgite and its application in ammonia nitrogen wastewater treatment, which has the following beneficial effects: Utilizing the high specific surface area and magnesium-rich background of attapulgite, a "titanium-magnesium-attapulgite" activated structure is constructed by simultaneously adding titanium and magnesium sources for co-precipitation and using a differentiated stirring and shearing strategy (low-speed dispersion, high-speed precipitation). This method eliminates the need for expensive high-pressure hydrothermal equipment and uses an atmospheric pressure aging process to prepare a modified attapulgite adsorbent material with high adsorption capacity, high stability, and low cost. It can maintain a removal rate of over 90% for low-concentration ammonia nitrogen (5 mg / L) and a removal rate of over 60% for high-concentration ammonia nitrogen (50 mg / L) within 60 minutes. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] Raw material description:

[0030] 1. Attapulgite soil (i.e., original attapulgite soil), sourced from Xuyi, Jiangsu Province, with a particle size of 200 mesh and a specific surface area of ​​126.3 m². 2 / g, main oxide composition, by mass percentage: SiO2 58.2%, Al2O3 9.5%, Fe2O3 6.2%, Na2O 0.07%, K2O 1.12%, CaO 1.21%, MgO 11.0%, MnO 0.61%, TiO2 0.48%, loss on ignition: 11.2%.

[0031] 2. The titanium salt is TiOSO4.

[0032] 3. The magnesium salt is MgCl2·6H2O.

[0033] 4. The preparation method of acid-activated attapulgite is as follows:

[0034] S1. Add water to attapulgite to prepare a slurry with a mass concentration of 5%. After stirring and dispersing, allow it to settle by gravity for 6 hours. Take the upper slurry, centrifuge to dehydrate, and dry at 10000 r / min for 10 min at 105℃ to obtain purified attapulgite.

[0035] S2. Add 2 mol / L sulfuric acid to the attapulgite purified in step S1, with a solid-liquid ratio of 1:10, that is, the mass ratio of the attapulgite purified in step 1 to the volume ratio of sulfuric acid is 1:10. Stir at 60°C for 3 hours, let stand for 8 hours, remove the upper turbid liquid, and retain the bottom precipitate. The bottom precipitate is the acid-activated attapulgite.

[0036] S3. Wash the precipitate obtained in step S2 repeatedly with deionized water, centrifuge, discard the supernatant, and repeat this step until the supernatant pH is 6.5-7.

[0037] S4. Dry the precipitate obtained in step S3 at 105-110℃ and grind it to 200 mesh. Coarse particles will lead to poor dispersibility of the subsequent suspension. Fine powder has a large specific surface area, but in the subsequent "hydrothermal reaction" step, excessively fine particles are prone to "agglomeration" and re-form into large particles, which will block the pores. Therefore, the particle size of attapulgite is selected to be 200-400 mesh.

[0038] A method for preparing acid-salt activated attapulgite includes the following steps:

[0039] 1. Preparation of titanium salt solution, magnesium salt solution and acid-activated attapulgite slurry;

[0040] To prepare the titanium salt solution, 0.05 mol TiOSO4 was dissolved in 50 ml of 1.0 mol / L dilute sulfuric acid and stirred until completely dissolved.

[0041] To prepare the magnesium salt solution, dissolve 0.12 mol of magnesium chloride hexahydrate in 100 ml of deionized water and stir until completely dissolved.

[0042] Preparation of acid-activated attapulgite slurry: 100g of acid-activated attapulgite was added to 850ml of deionized water and stirred to disperse into a slurry.

[0043] 2. The titanium salt solution and magnesium salt solution prepared in step 1 are simultaneously added to the acid-activated attapulgite slurry and dispersed evenly to obtain a mixed slurry of titanium salt, magnesium salt and attapulgite.

[0044] The stirring was carried out at a low speed of 300 r / min for 1 hour, and the temperature was controlled at 60℃.

[0045] In the titanium-magnesium-attapulgite mixed slurry, the solid-liquid ratio of attapulgite is 1:10 (the mass ratio of acid-activated attapulgite to the volume ratio of the mixed slurry is 1:10, and water can be added according to the mixing situation). For every 100g of acid-activated attapulgite, 0.05mol of titanium salt is added, and the molar ratio of titanium salt to magnesium salt is 1:2.4 (Ti... 4+ :Mg 2+ The molar ratio is 1:2.4).

[0046] 3. Add 1 mol / L NaOH solution dropwise to the titanium salt-magnesium salt-attapulgite mixed slurry prepared in step 2 above, while stirring, and adjust the pH to 9-10 to obtain a mixed slurry with load settling.

[0047] Compared to step 2, step 3 increases the stirring speed to 600 r / min and controls the dropping speed at 2 drops / second to effectively disperse the settled particles and distribute them evenly.

[0048] 4. Transfer the mixed slurry obtained in step 3 to 60℃ and let it stand for 5 hours to age;

[0049] Compared to high-temperature aging at 120-150℃, the former has lower crystallinity, maintains effective dispersion, has a larger specific surface area, and richer pores, making it more suitable for ammonia nitrogen adsorption applications in wastewater.

[0050] 5. After the reaction in step 4, the mixed slurry with load sedimentation is cooled to room temperature, centrifuged at 5000 r / min for 5 min, deionized water is added to the precipitate in the centrifuge tube, and the precipitate is shaken and dispersed to resuspend. The centrifugation-resuspending and washing process is repeated 3-4 times, centrifuged at 5000 r / min for 5 min, and vacuum dried at 90℃ for 8-12 hours (to prevent thermal sintering and deactivation caused by excessive drying temperature). The mixture is then ground to obtain the finished product.

[0051] Example 2

[0052] A method for preparing acid-salt activated attapulgite includes the following steps:

[0053] 1. Preparation of titanium salt solution, magnesium salt solution and acid-activated attapulgite slurry;

[0054] To prepare the titanium salt solution, 0.05 mol TiOSO4 was dissolved in 50 ml of 1.0 mol / L dilute sulfuric acid and stirred until completely dissolved.

[0055] To prepare the magnesium salt solution, dissolve 0.075 mol of magnesium chloride hexahydrate in 100 ml of deionized water and stir until completely dissolved.

[0056] Preparation of acid-activated attapulgite slurry: 100g of acid-activated attapulgite was added to 850ml of deionized water and stirred to disperse into a slurry.

[0057] 2. The titanium salt solution and magnesium salt solution prepared in step 1 are simultaneously added to the acid-activated attapulgite slurry. The mixture is stirred at a low speed of 300 r / min for 1 hour, and the temperature is controlled at 60℃. The mixture is dispersed evenly to obtain a mixed slurry of titanium salt, magnesium salt and attapulgite.

[0058] In the mixed slurry of titanium salt, magnesium salt and attapulgite, the solid-liquid ratio of attapulgite is 1:10, and 0.05 mol of titanium salt is added for every 100g of acid-activated attapulgite. The molar ratio of titanium salt to magnesium salt is 1:1.5.

[0059] 3. Add 1 mol / L NaOH solution dropwise to the titanium salt-magnesium salt-attapulgite mixed slurry prepared in step 2 above, while stirring, and adjust the pH to 9-10 to obtain a mixed slurry with load settling.

[0060] Compared to step 2, step 3 increases the stirring speed to 600 r / min and controls the dropping speed at 2 drops / second to effectively disperse the settled particles and distribute them evenly.

[0061] 4. Transfer the mixed slurry obtained in step 3 to 60℃ and let it stand for 5 hours to age;

[0062] 5. After the reaction in step 4, the mixed slurry with load sedimentation is cooled to room temperature, centrifuged at 5000 r / min for 5 min, deionized water is added to the precipitate in the centrifuge tube, and the precipitate is shaken and resuspended. The centrifugation-resuspending and washing process is repeated 3-4 times, centrifuged at 5000 r / min for 5 min, vacuum dried at 90℃ for 12 hours, and ground to obtain the finished product.

[0063] Example 3

[0064] A method for preparing acid-salt activated attapulgite includes the following steps:

[0065] 1. Preparation of titanium salt solution, magnesium salt solution and acid-activated attapulgite slurry;

[0066] To prepare the titanium salt solution, 0.05 mol TiOSO4 was dissolved in 50 ml of 1.0 mol / L dilute sulfuric acid and stirred until completely dissolved.

[0067] To prepare the magnesium salt solution, dissolve 0.09 mol of magnesium chloride hexahydrate in 100 ml of deionized water and stir until completely dissolved.

[0068] Preparation of acid-activated attapulgite slurry: 100g of acid-activated attapulgite was added to 850ml of deionized water and stirred to disperse into a slurry.

[0069] 2. The titanium salt solution and magnesium salt solution prepared in step 1 are simultaneously added to the acid-activated attapulgite slurry. The mixture is stirred at a low speed of 300 r / min for 1 hour, and the temperature is controlled at 60℃. The mixture is dispersed evenly to obtain a mixed slurry of titanium salt, magnesium salt and attapulgite.

[0070] In the mixed slurry of titanium salt, magnesium salt and attapulgite, the solid-liquid ratio of attapulgite is 1:10, and 0.05 mol of titanium salt is added for every 100g of acid-activated attapulgite. The molar ratio of titanium salt to magnesium salt is 1:1.8.

[0071] 3. Add 1 mol / L NaOH solution dropwise to the titanium salt-magnesium salt-attapulgite mixed slurry prepared in step 2 above, while stirring, and adjust the pH to 9-10 to obtain a mixed slurry with load settling.

[0072] 4. Transfer the mixed slurry obtained in step 3 to 60℃ and let it stand for 5 hours to age;

[0073] 5. After the reaction in step 4, the mixed slurry with load sedimentation is cooled to room temperature, centrifuged at 5000 r / min for 5 min, deionized water is added to the precipitate in the centrifuge tube, and the precipitate is shaken and resuspended. The centrifugation-resuspending and washing process is repeated 3-4 times, centrifuged at 5000 r / min for 5 min, vacuum dried at 90℃ for 12 hours, and ground to obtain the finished product.

[0074] Example 4

[0075] A method for preparing acid-salt activated attapulgite includes the following steps:

[0076] 1. Preparation of titanium salt solution, magnesium salt solution and acid-activated attapulgite slurry;

[0077] To prepare the titanium salt solution, 0.05 mol TiOSO4 was dissolved in 50 ml of 1.0 mol / L dilute sulfuric acid and stirred until completely dissolved.

[0078] To prepare the magnesium salt solution, dissolve 0.10 mol of magnesium chloride hexahydrate in 100 ml of deionized water and stir until completely dissolved.

[0079] Preparation of acid-activated attapulgite slurry: 100g of acid-activated attapulgite was added to 850ml of deionized water and stirred to disperse into a slurry.

[0080] 2. The titanium salt solution and magnesium salt solution prepared in step 1 are simultaneously added to the acid-activated attapulgite slurry. The mixture is stirred at a low speed of 300 r / min for 1 hour, and the temperature is controlled at 60℃. The mixture is dispersed evenly to obtain a mixed slurry of titanium salt, magnesium salt and attapulgite.

[0081] In the mixed slurry of titanium salt, magnesium salt and attapulgite, the solid-liquid ratio of attapulgite is 1:10, and 0.05 mol of titanium salt is added for every 100g of acid-activated attapulgite. The molar ratio of titanium salt to magnesium salt is 1:2.0.

[0082] 3. Add 1 mol / L NaOH solution dropwise to the titanium salt-magnesium salt-attapulgite mixed slurry prepared in step 2 above, while stirring, and adjust the pH to 9-10 to obtain a mixed slurry with load settling.

[0083] Compared to step 2, step 3 increases the stirring speed to 600 r / min and controls the dropping speed at 2 drops / second to effectively disperse the settled particles and distribute them evenly.

[0084] 4. Transfer the mixed slurry obtained in step 3 to 60℃ and let it stand for 5 hours to age;

[0085] 5. After the reaction in step 4, the mixed slurry with load sedimentation is cooled to room temperature, centrifuged at 5000 r / min for 5 min, deionized water is added to the precipitate in the centrifuge tube, and the precipitate is shaken and resuspended. The centrifugation-resuspending and washing process is repeated 3-4 times, centrifuged at 5000 r / min for 5 min, vacuum dried at 90℃ for 12 hours, and ground to obtain the finished product.

[0086] Example 5

[0087] A method for preparing acid-salt activated attapulgite includes the following steps:

[0088] 1. Preparation of titanium salt solution, magnesium salt solution and acid-activated attapulgite slurry;

[0089] To prepare the titanium salt solution, 0.05 mol TiOSO4 was dissolved in 50 ml of 1.0 mol / L dilute sulfuric acid and stirred until completely dissolved.

[0090] To prepare the magnesium salt solution, dissolve 0.11 mol of magnesium chloride hexahydrate in 100 ml of deionized water and stir until completely dissolved.

[0091] Preparation of acid-activated attapulgite slurry: 100g of acid-activated attapulgite was added to 850ml of deionized water and stirred to disperse into a slurry.

[0092] 2. The titanium salt solution and magnesium salt solution prepared in step 1 are simultaneously added to the acid-activated attapulgite slurry. The mixture is stirred at a low speed of 300 r / min for 1 hour, and the temperature is controlled at 60℃. The mixture is dispersed evenly to obtain a mixed slurry of titanium salt, magnesium salt and attapulgite.

[0093] In the mixed slurry of titanium salt, magnesium salt and attapulgite, the solid-liquid ratio of attapulgite is 1:10, and 0.05 mol of titanium salt is added for every 100g of acid-activated attapulgite. The molar ratio of titanium salt to magnesium salt is 1:2.2.

[0094] 3. Add 1 mol / L NaOH solution dropwise to the titanium salt-magnesium salt-attapulgite mixed slurry prepared in step 2 above, while stirring, and adjust the pH to 9-10 to obtain a mixed slurry with load settling.

[0095] Compared to step 2, step 3 increases the stirring speed to 600 r / min and controls the dropping speed at 2 drops / second to effectively disperse the settled particles and distribute them evenly.

[0096] 4. Transfer the mixed slurry obtained in step 3 to 60℃ and let it stand for 5 hours to age;

[0097] 5. After the reaction in step 4, the mixed slurry with load sedimentation is cooled to room temperature, centrifuged at 5000 r / min for 5 min, deionized water is added to the precipitate in the centrifuge tube, and the precipitate is shaken and resuspended. The centrifugation-resuspending and washing process is repeated 3-4 times, centrifuged at 5000 r / min for 5 min, vacuum dried at 90℃ for 12 hours, and ground to obtain the finished product.

[0098] Example 6

[0099] A method for preparing acid-salt activated attapulgite includes the following steps:

[0100] 1. Preparation of titanium salt solution, magnesium salt solution and acid-activated attapulgite slurry;

[0101] To prepare the titanium salt solution, 0.05 mol TiOSO4 was dissolved in 50 ml of 1.0 mol / L dilute sulfuric acid and stirred until completely dissolved.

[0102] To prepare the magnesium salt solution, dissolve 0.125 mol of magnesium chloride hexahydrate in 100 ml of deionized water and stir until completely dissolved.

[0103] Preparation of acid-activated attapulgite slurry: 100g of acid-activated attapulgite was added to 850ml of deionized water and stirred to disperse into a slurry.

[0104] 2. The titanium salt solution and magnesium salt solution prepared in step 1 are simultaneously added to the acid-activated attapulgite slurry. The mixture is stirred at a low speed of 300 r / min for 1 hour, and the temperature is controlled at 60℃. The mixture is dispersed evenly to obtain a mixed slurry of titanium salt, magnesium salt and attapulgite.

[0105] In the mixed slurry of titanium salt, magnesium salt and attapulgite, the solid-liquid ratio of attapulgite is 1:10, and 0.05 mol of titanium salt is added for every 100g of acid-activated attapulgite. The molar ratio of titanium salt to magnesium salt is 1:2.5.

[0106] 3. Add 1 mol / L NaOH solution dropwise to the titanium salt-magnesium salt-attapulgite mixed slurry prepared in step 2 above, while stirring, and adjust the pH to 9-10 to obtain a mixed slurry with load settling.

[0107] Compared to step 2, step 3 increases the stirring speed to 600 r / min and controls the dropping speed at 2 drops / second to effectively disperse the settled particles and distribute them evenly.

[0108] 4. Transfer the mixed slurry obtained in step 3 to 60℃ and let it stand for 5 hours to age;

[0109] 5. After the reaction in step 4, the mixed slurry with load sedimentation is cooled to room temperature, centrifuged at 5000 r / min for 5 min, deionized water is added to the precipitate in the centrifuge tube, and the precipitate is shaken and resuspended. The centrifugation-resuspending and washing process is repeated 3-4 times, centrifuged at 5000 r / min for 5 min, vacuum dried at 90℃ for 12 hours, and ground to obtain the finished product.

[0110] Comparative Example 1

[0111] A method for preparing acid-salt activated attapulgite includes the following steps:

[0112] 1. Preparation of titanium salt solution, magnesium salt solution and acid-activated attapulgite slurry;

[0113] To prepare the titanium salt solution, 0.05 mol TiOSO4 was dissolved in 50 ml of 1.0 mol / L dilute sulfuric acid and stirred until completely dissolved.

[0114] To prepare the magnesium salt solution, dissolve 0.06 mol of magnesium chloride hexahydrate in 100 ml of deionized water and stir until completely dissolved.

[0115] Preparation of acid-activated attapulgite slurry: 100g of acid-activated attapulgite was added to 850ml of deionized water and stirred to disperse into a slurry.

[0116] 2. The titanium salt solution and magnesium salt solution prepared in step 1 are simultaneously added to the acid-activated attapulgite slurry. The mixture is stirred at a low speed of 300 r / min for 1 hour, and the temperature is controlled at 60℃. The mixture is dispersed evenly to obtain a mixed slurry of titanium salt, magnesium salt and attapulgite.

[0117] In the mixed slurry of titanium salt, magnesium salt and attapulgite, the solid-liquid ratio of attapulgite is 1:10, and 0.05 mol of titanium salt is added for every 100g of acid-activated attapulgite. The molar ratio of titanium salt to magnesium salt is 1:1.2.

[0118] 3. Add 1 mol / L NaOH solution dropwise to the titanium salt-magnesium salt-attapulgite mixed slurry prepared in step 2 above, while stirring, and adjust the pH to 9-10 to obtain a mixed slurry with load settling.

[0119] Compared to step 2, step 3 increases the stirring speed to 600 r / min and controls the dropping speed at 2 drops / second to effectively disperse the settled particles and distribute them evenly.

[0120] 4. Transfer the mixed slurry obtained in step 3 to 60℃ and let it stand for 5 hours to age;

[0121] 5. After the reaction in step 4, the mixed slurry with load sedimentation is cooled to room temperature, centrifuged at 5000 r / min for 5 min, deionized water is added to the precipitate in the centrifuge tube, and the precipitate is shaken and resuspended. The centrifugation-resuspending and washing process is repeated 3-4 times, centrifuged at 5000 r / min for 5 min, vacuum dried at 90℃ for 12 hours, and ground to obtain the finished product.

[0122] Comparative Example 2

[0123] A method for preparing acid-salt activated attapulgite includes the following steps:

[0124] 1. Preparation of titanium salt solution, magnesium salt solution and acid-activated attapulgite slurry;

[0125] To prepare the titanium salt solution, 0.05 mol TiOSO4 was dissolved in 50 ml of 1.0 mol / L dilute sulfuric acid and stirred until completely dissolved.

[0126] To prepare the magnesium salt solution, dissolve 0.15 mol of magnesium chloride hexahydrate in 100 ml of deionized water and stir until completely dissolved.

[0127] Preparation of acid-activated attapulgite slurry: 100g of acid-activated attapulgite was added to 850ml of deionized water and stirred to disperse into a slurry.

[0128] 2. The titanium salt solution and magnesium salt solution prepared in step 1 are simultaneously added to the acid-activated attapulgite slurry. The mixture is stirred at a low speed of 300 r / min for 1 hour, and the temperature is controlled at 60℃. The mixture is dispersed evenly to obtain a mixed slurry of titanium salt, magnesium salt and attapulgite.

[0129] In the mixed slurry of titanium salt, magnesium salt and attapulgite, the solid-liquid ratio of attapulgite is 1:10, and 0.05 mol of titanium salt is added for every 100g of acid-activated attapulgite. The molar ratio of titanium salt to magnesium salt is 1:3.0.

[0130] 3. Add 1 mol / L NaOH solution dropwise to the titanium salt-magnesium salt-attapulgite mixed slurry prepared in step 2 above, while stirring, and adjust the pH to 9-10 to obtain a mixed slurry with load settling.

[0131] Compared to step 2, step 3 increases the stirring speed to 600 r / min and controls the dropping speed at 2 drops / second to effectively disperse the settled particles and distribute them evenly.

[0132] 4. Transfer the mixed slurry obtained in step 3 to 60℃ and let it stand for 5 hours to age;

[0133] 5. After the reaction in step 4, the mixed slurry with load sedimentation is cooled to room temperature, centrifuged at 5000 r / min for 5 min, deionized water is added to the precipitate in the centrifuge tube, and the precipitate is shaken and resuspended. The centrifugation-resuspending and washing process is repeated 3-4 times, centrifuged at 5000 r / min for 5 min, vacuum dried at 90℃ for 12 hours, and ground to obtain the finished product.

[0134] Comparative Example 3

[0135] A method for preparing acid-salt activated attapulgite includes the following steps:

[0136] 1. Preparation of titanium salt solution and acid-activated attapulgite slurry;

[0137] To prepare the titanium salt solution, 0.18 mol TiOSO4 was dissolved in 180 ml of 1.0 mol / L dilute sulfuric acid and stirred until completely dissolved.

[0138] Preparation of acid-activated attapulgite slurry: 100g of acid-activated attapulgite was added to 850ml of deionized water and stirred to disperse into a slurry.

[0139] 2. Add the titanium salt solution prepared in step 1 to the acid-activated attapulgite slurry, disperse it evenly, stir at a low speed of 300 r / min for 1 h, and control the temperature at 60℃ to obtain a titanium salt-attapulgite mixed slurry.

[0140] 3. Add 1 mol / L NaOH solution dropwise to the titanium salt-attapulgite mixed slurry prepared in step 2 above, while stirring, and adjust the pH to 9-10 to obtain a mixed slurry with load settling.

[0141] Compared to step 2, step 3 increases the stirring speed to 600 r / min and controls the dropping speed at 2 drops / second to effectively disperse the settled particles and distribute them evenly.

[0142] 4. Transfer the mixed slurry obtained in step 3 to 60°C and let it stand for 5 hours.

[0143] 5. After the reaction in step 4, the mixed slurry with load sedimentation is cooled to room temperature, centrifuged at 5000 r / min for 5 min, deionized water is added to the precipitate in the centrifuge tube, and the precipitate is shaken and resuspended. The centrifugation-resuspending and washing process is repeated 3-4 times, centrifuged at 5000 r / min for 5 min, vacuum dried at 90℃ for 12 hours, and ground to obtain the finished product.

[0144] Comparative Example 4

[0145] A method for preparing acid-salt activated attapulgite includes the following steps:

[0146] 1. Preparation of magnesium salt solution and acid-activated attapulgite slurry;

[0147] To prepare the magnesium salt solution, dissolve 0.18 mol of magnesium chloride hexahydrate in 100 ml of deionized water and stir until completely dissolved.

[0148] Preparation of acid-activated attapulgite slurry: 100g of acid-activated attapulgite was added to 850ml of deionized water and stirred to disperse into a slurry.

[0149] 2. Add the magnesium salt solution prepared in step 1 to the acid-activated attapulgite slurry, disperse it evenly, stir at a low speed of 300 r / min for 1 h, and control the temperature at 60℃ to obtain a magnesium salt-attapulgite mixed slurry.

[0150] 3. Add 1 mol / L NaOH solution dropwise to the magnesium salt-attapulgite mixed slurry prepared in step 2 above, while stirring, and adjust the pH to 9-10 to obtain a mixed slurry with load settling.

[0151] Compared to step 2, step 3 increases the stirring speed to 600 r / min and controls the dropping speed at 2 drops / second to effectively disperse the settled particles and distribute them evenly.

[0152] 4. Transfer the mixed slurry obtained in step 3 to 60℃ and let it stand for 5 hours to age;

[0153] 5. After the reaction in step 4, the mixed slurry with load sedimentation is cooled to room temperature, centrifuged at 5000 r / min for 5 min, deionized water is added to the precipitate in the centrifuge tube, and the precipitate is shaken and resuspended. The centrifugation-resuspending and washing process is repeated 3-4 times, centrifuged at 5000 r / min for 5 min, vacuum dried at 90℃ for 12 hours, and ground to obtain the finished product.

[0154] Application instructions:

[0155] To simulate ammonia nitrogen wastewater, NH4Cl was dissolved in deionized water to prepare simulated ammonia nitrogen wastewater at concentrations of 5 mg / L and 50 mg / L.

[0156] Take the activated attapulgite product obtained in the above examples / comparative examples, with a particle size of 200 mesh and a mass of 1g, add it to 100ml of simulated ammonia nitrogen wastewater, stir magnetically at 200r / min for 60min, let it stand for 30min, take the supernatant, and measure the ammonia nitrogen concentration using the salicylic acid spectrophotometric method.

[0157] The ammonia nitrogen removal rate is calculated as follows: R = [(C0 - Ce) / C0] × 100%;

[0158] R: Ammonia nitrogen removal rate;

[0159] C0: Initial ammonia nitrogen concentration in the simulated ammonia nitrogen wastewater, in mg / L;

[0160] Ce: The concentration of ammonia nitrogen in simulated ammonia nitrogen wastewater after adsorption by activated attapulgite, in mg / L.

[0161] Adsorption equilibrium time: For the adsorption of simulated ammonia nitrogen wastewater with a concentration of 50 g / L, a set of time gradient experiments were conducted. The absorbance was measured every 5 minutes. When the concentration change at adjacent time points was no longer significant, this time was called the "adsorption equilibrium time".

[0162] The results of the ammonia nitrogen removal rate and equilibrium time tests are shown in the table below.

[0163] Serial Number <![CDATA[Titanium-magnesium molar ratio (Ti 4 ⁺:Mg²⁺)]]> Ammonia nitrogen removal rate (%) in simulated wastewater at a concentration of 5 g / L Ammonia nitrogen removal rate (%) in simulated wastewater at a concentration of 50 g / L Adsorption equilibrium time (min) 1 1：1.2 88.5 52.0 85 2 1：1.5 92.0 63.5 59 3 1：1.8 94.5 73.0 45 4 1：2.0 96.2 80.5 38 5 1：2.2 97.7 86.9 34 6 1：2.4 99.6 88.0 30 7 1：2.5 97.5 86.5 33 8 1：3.0 91.0 76.5 100 9 Single titanium salt 75.0 38.6 60 10 Single magnesium salt 95.7 68.2 120

[0164] Attapulgite activated with acid and salt, at a titanium-magnesium molar ratio of 1:1.5–1:2.5, can maintain a removal rate of over 90% for low-concentration ammonia nitrogen (5 mg / L) and over 60% for high-concentration ammonia nitrogen (50 mg / L) within 60 minutes. The optimal effect is achieved at a titanium-magnesium molar ratio of 1:2.4, with a removal rate of 99.6% for low-concentration ammonia nitrogen (5 mg / L) and 88% for high-concentration ammonia nitrogen (50 mg / L). This demonstrates that the modified process successfully prepared an adsorbent material with highly active sites and a good pore structure, showing great application potential in the field of ammonia nitrogen treatment.

[0165] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0166] 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 acid-salt activated attapulgite, characterized in that, Includes the following steps: Step 1. Prepare titanium salt solution, magnesium salt solution and acid-activated attapulgite slurry; Step 2. Add the titanium salt solution and magnesium salt solution simultaneously to the acid-activated attapulgite slurry and disperse them evenly to obtain a mixed slurry of titanium salt, magnesium salt and attapulgite. In the mixed slurry of titanium salt, magnesium salt and attapulgite, the solid-liquid ratio of attapulgite is 1:8-1:12, and 0.03mol-0.06mol of titanium salt is added for every 100g of acid-activated attapulgite. The molar ratio of titanium salt to magnesium salt is 1:1.5-1:2.

5. Step 3. Add 1-2 mol / L NaOH solution dropwise to the titanium salt-magnesium salt-attapulgite mixed slurry prepared in Step 2 above, while stirring, and adjust the pH to 9-10 to obtain a mixed slurry with load settling. Step 4. Transfer the mixed slurry obtained in Step 3 under load and allow it to stand at 60℃ for 4-6 hours to age. Step 5. The mixed slurry obtained after the reaction in Step 4 is cooled, centrifuged, resuspended and washed, centrifuged again, dried and ground to obtain the finished product.

2. The method for preparing acid-salt activated attapulgite according to claim 1, characterized in that, The titanium salt is TiOSO4.

3. The method for preparing acid-salt activated attapulgite according to claim 2, characterized in that, The magnesium salt is MgCl2 or MgSO4.

4. A method for preparing acid-salt activated attapulgite according to any one of claims 1-3, characterized in that, For every 100g of acid-activated attapulgite, add 0.04-0.05mol of titanium salt, with a molar ratio of TiOSO4 to MgCl2 of 1:2.0-1:2.

5.

5. The method for preparing acid-salt activated attapulgite according to claim 4, characterized in that, For every 100g of acid-activated attapulgite, 0.05mol of titanium salt is added, and the molar ratio of TiOSO4 to MgCl2 is 1:2.

4.

6. The method for preparing acid-salt activated attapulgite according to claim 1, characterized in that, In step 2, a low-speed stirring of 300-500 r / min is used for 1 hour, and the temperature is controlled at 60-70℃. In step 3, the stirring speed is increased to 600-800 r / min, and the dropping speed is controlled at 2-5 drops / second.

7. The method for preparing acid-salt activated attapulgite according to claim 1, characterized in that, In step 2, the acid-activated attapulgite is obtained by the following method: S1. Add water to attapulgite to prepare a slurry with a mass concentration of 5%-10%. After stirring and dispersing, allow it to settle by gravity. Take the upper layer of slurry, dehydrate and dry it to obtain purified attapulgite. S2. Add 2 mol / L-4 mol / L hydrochloric acid or sulfuric acid to the attapulgite purified in step S1, with a solid-liquid ratio of 1:

10. Stir at 60-80℃ for 2-4 hours, let stand for 4-8 hours, remove the upper turbid liquid, and retain the bottom precipitate. The bottom precipitate is the acid-activated attapulgite. S3. Wash the precipitate obtained in step S2 repeatedly with deionized water, centrifuge, discard the supernatant, and repeat this step until the supernatant pH is 6.5-7. S4. Dry the precipitate obtained in step S3 at 105-110℃ and grind it to 200-400 mesh.

8. The application of acid-activated attapulgite as described in any one of claims 1-3 and 6-7 in the treatment of ammonia nitrogen wastewater.