Preparation method of salt-template agent synergistically activated attapulgite and application of attapulgite in hierarchical pore adsorption material

Abstract

The invention relates to the technical field of porous material preparation, and provides a preparation method of salt-template agent synergistically activated attapulgite and application of the salt-template agent synergistically activated attapulgite in a hierarchical porous adsorbing material.The preparation method comprises the following steps that S1, pretreatment is conducted, specifically, attapulgite raw ore is crushed, screened, purified through a wet method and then dried, the purified and dried attapulgite is added into diluted hydrochloric acid with the concentration of 0.5-1.0 mol / L, and the mixture is stirred to be uniform; the solid-to-liquid ratio is 1: 10, stirring at 60 DEG C for 2 hours, carrying out acid treatment, centrifugally washing to be neutral, and drying for later use; the activated attapulgite prepared by the method disclosed by the invention shows an ultrahigh adsorption removal rate on typical macromolecular pollutants. Under the same dosage, the removal rate of the product to macromolecular pollutants is obviously superior to that of a contrast sample, which proves that the method can greatly improve the treatment capacity of the attapulgite, and after high-temperature calcination, the main component of the obtained activated attapulgite is converted into a silicate oxide phase with high thermal stability, so that the treatment effect is greatly improved. Secondary pollution caused by dissolution during use is not easy to occur, and the adsorbent can be used as an efficient and low-cost adsorbent.

Description

Technical Field

[0001] This invention relates to the field of porous material preparation technology, specifically to a method for preparing attapulgite synergistically activated by salt and template agent and its application in hierarchical porous adsorption materials. Background Technology

[0002] Hierarchical porous materials (possessing micropores, mesopores, and macropores simultaneously) have advantages in the adsorption of macromolecular organic matter. Attapulgite itself has microporous and mesoporous structures, but its macropores are insufficient, which limits the diffusion and adsorption of macromolecular organic matter.

[0003] Salt solution modification can regulate surface charge and pore structure; organic template agents (such as CTAB) can self-assemble into mesoporous or macroporous structures on mineral surfaces. The synergistic use of salt and template agents holds promise for constructing hierarchical porous structures and improving the adsorption performance for macromolecular organic compounds. However, existing technologies lack a salt-templating agent synergistic activation process for attapulgite. Therefore, we propose a method for preparing salt-templating agent synergistically activated attapulgite and its application in hierarchical porous adsorption materials. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing attapulgite synergistically activated by salt and template agents and its application in hierarchical porous adsorption materials. This method overcomes the deficiencies of existing technologies, features a reasonable design and compact structure, and solves the problem of the lack of a salt-template agent synergistic activation process for attapulgite in existing technologies.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing attapulgite soil with synergistic activation by salt and template agent, comprising the following steps: S1. Pretreatment: The raw attapulgite ore is crushed, screened, purified by wet process, and then dried. The purified and dried attapulgite soil is added to 0.5–1.0 mol / L dilute hydrochloric acid at a solid-liquid ratio of 1:10 and stirred at 60℃ for 2 h. After acid treatment, it is centrifuged and washed until neutral and then dried for later use. S2. Preparation of salt-template mixture: Prepare a MgCl2 solution with a concentration of 0.1–0.5 mol / L, and add hexadecyltrimethylammonium bromide (CTAB) to make the CTAB concentration 0.01–0.1 mol / L. Finally, add polyethylene glycol PEG-1000 with a concentration of 1–5 g / L. S3. Mixing and activating: The attapulgite soil pretreated in step S1 is mixed with the salt-template agent mixed solution prepared in step S2 at a solid-liquid mass ratio of 1:5–1:20, and stirred at 40–80℃ for 4–12 h. S4. Solid-liquid separation and drying: The mixture after the reaction in step S3 is subjected to solid-liquid separation, the solid product is collected and dried at 80–120℃; S5. Calcination: The solid dried in step S4 is calcined at 300–550℃ for 2–4 h and then naturally cooled to room temperature to obtain the salt-template agent synergistic activated attapulgite.

[0006] Preferably, after the mixing and activation in step S3 and before the solid-liquid separation in step S4, an ultrasonic dispersion step is further included: subjecting the mixture to ultrasonic treatment at a frequency of 40–80 kHz for a time of 20–40 min.

[0007] Preferably, in step S3, the attapulgite pretreated in step S1 and the salt-template agent mixture prepared in step S2 are first stirred at 40-60°C for 2 hours, and then stirred at 60-80°C for 2-10 hours, while maintaining the pH of the reaction system at 8-9.

[0008] Preferably, the pH of the attapulgite and the prepared salt-template mixture solution is adjusted and maintained by adding dilute ammonia water in step S3.

[0009] Preferably, in step S3, the stirring speed is 200–600 r / min.

[0010] Preferably, in step S5, the dried solid is first calcined at 300-450℃ for 1 hour, and then calcined at 450-550℃ for 1-3 hours.

[0011] Preferably, the particle size of the attapulgite after screening in step S1 is no greater than 2 mm, and the wet purification process includes crushing the raw ore, adding water to make a suspension, adding a dispersant, and removing impurities by natural sedimentation or centrifugal separation.

[0012] Application of salt-templating agent synergistic activation of attapulgite in adsorbing macromolecular organic matter in aqueous solution.

[0013] Preferably, the macromolecular organic compound is humic acid or a macromolecular dye.

[0014] Preferably, the specific application method includes: (1) The salt-template agent is used to synergistically activate attapulgite, which is then added to an aqueous solution containing macromolecular organic matter. The amount of activated attapulgite added is 0.5–5 g / L. (2) The aqueous solution is stirred and contacted with the activated attapulgite at 20–40°C for 30–120 min; (3) Perform solid-liquid separation to obtain a purified aqueous solution. This invention provides a method for preparing attapulgite synergistically activated by salt and template agents and its application in hierarchical porous adsorption materials. It has the following beneficial effects: 1. The activated attapulgite prepared by this invention exhibits extremely high adsorption and removal rates for typical macromolecular pollutants. As shown in the application examples, at the same dosage, the product's removal rate for macromolecular pollutants is significantly better than that of the comparative sample. This proves that the method can greatly improve the treatment capacity of attapulgite. Furthermore, after high-temperature calcination, the organic components in the obtained activated attapulgite are completely removed, and the main components are converted into a highly thermally stable silicate oxide phase, which is less likely to leach out and cause secondary pollution during use. It also has great application potential in the field of wastewater containing macromolecular organic matter and can be used as a highly efficient and low-cost adsorbent.

[0015] 2. By combining magnesium salt (MgCl2), cationic surfactant (CTAB), and nonionic polymer (PEG-1000) under specific pH conditions, along with the programmed temperature calcination strategy designed in step S5, a multi-level pore system containing abundant micropores, mesopores, and even macropores was successfully constructed in attapulgite. This structure facilitates the rapid diffusion, mass transfer, and containment of macromolecular pollutants (such as humic acid and dyes), thereby significantly improving adsorption capacity and rate. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. 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.

[0017] Example 1

[0018] A method for preparing attapulgite soil with salt-templating agent synergistic activation includes the following steps: S1. Pretreatment: The raw attapulgite ore is crushed and sieved through a 2 mm standard sieve. The undersize material is collected and mixed with water to prepare a 15% (w / w) suspension. Sodium hexametaphosphate (0.5% by weight of the attapulgite) is added as a dispersant, and the mixture is stirred at high speed for 30 minutes. After settling for 4 hours, the bottom sand and gravel and the upper turbid liquid are discarded. The middle suspension is collected and centrifuged to obtain purified attapulgite. The purified soil is dried at 105℃ to constant weight. 100g of the dried purified soil is weighed and 1.0 L of 0.5 mol / L dilute hydrochloric acid (solid-liquid ratio 1:10) is added. The mixture is mechanically stirred in a 60℃ water bath for 2 hours. After the reaction, the mixture is centrifuged, and the solid is repeatedly washed with deionized water until the pH of the effluent is neutral. The solid is then dried again at 105℃ for 12 hours to obtain acid-pretreated attapulgite, which is then ground and used for further processing.

[0019] S2. Preparation of the salt-template mixture: Weigh 4.76 g of MgCl2·6H2O and dissolve it in 100 mL of deionized water to prepare a 0.2 mol / L MgCl2 solution. Add 0.36 g of hexadecyltrimethylammonium bromide (CTAB) to this solution and stir until completely dissolved. At this point, the CTAB concentration is 0.01 mol / L. Finally, add 0.10 g of polyethylene glycol PEG-1000 and stir to dissolve, obtaining a clear salt-template mixture.

[0020] S3. Mixing and Activation: Weigh 10 g of the acid-pretreated attapulgite prepared in step S1 and mix it with 100 mL of the salt-template mixture (solid-liquid mass ratio 1:10) prepared in step S2 in a three-necked flask. In a 50℃ water bath, stir at 300 r / min for 2 hours to ensure the solution fully penetrates the attapulgite. Then, raise the water bath temperature to 70℃ and stir at 500 r / min for 5 hours. Measure the pH of the reaction system in real time. Maintain the pH within the range of 8.5 ± 0.2 by adding dilute ammonia dropwise. Alkaline conditions promote the formation and stability of CTAB micelles.

[0021] S4. Solid-liquid separation and drying: After the reaction is complete, filter the mixture and collect the solid product. Wash three times each with deionized water and anhydrous ethanol. Place the washed solid in an oven and dry at 100°C for 6 hours.

[0022] S5. Calcination: The dried solid was placed in a muffle furnace and heated to 400°C at a rate of 2°C / min, and held at this temperature for 1 hour to allow CTAB and polyethylene glycol PEG-1000 to slowly decompose, forming a mesoporous / macroporous structure. Then, the temperature was increased to 500°C at a rate of 5°C / min and held at this temperature for 2 hours to completely decompose dilute ammonia and residual organic matter, generating micropores and simultaneously enhancing the crystallinity of the pore walls. After calcination, the sample was naturally cooled to room temperature and ground through a 200-mesh sieve to obtain the salt-template agent synergistically activated attapulgite sample, denoted as A1.

[0023] Example 2

[0024] A method for preparing attapulgite soil with salt-templating agent synergistic activation includes the following steps: S1. Pretreatment: Same as step S1 in Example 1, to obtain acid-pretreated attapulgite.

[0025] S2. Preparation of the salt-template mixture: Weigh 9.52 g of MgCl2·6H2O and dissolve it in 100 mL of deionized water to prepare a 0.4 mol / L MgCl2 solution. Add 1.82 g of CTAB to this solution and stir to dissolve (CTAB concentration is 0.05 mol / L). Finally, add 0.40 g of PEG-1000 and stir to dissolve.

[0026] S3. Mixing and Activation: Weigh 5 g of acid-pretreated attapulgite and mix it with 100 mL of the salt-template mixture (solid-liquid mass ratio 1:20) prepared in step S2. First, stir the mixture at 300 r / min for 2 hours at 40℃, then slowly adjust the pH of the system to 8.5 with dilute ammonia (volume ratio 1:10). Subsequently, raise the temperature to 80℃, maintain the pH within the range of 8.5±0.2, and continue stirring at 500 r / min for 6 hours.

[0027] S4. Ultrasonic treatment: After the reaction is complete, transfer the mixture to an ultrasonic cleaner and ultrasonically disperse it at a frequency of 60 kHz for 30 minutes.

[0028] S5. Solid-liquid separation and drying: After ultrasonication, centrifuge to collect the solid. Wash with deionized water until no chloride ions are detected (test with AgNO3 solution). Dry the solid at 110℃ for 8 hours.

[0029] S6. Calcination: The dried solid was placed in a muffle furnace, heated to 400℃ at 3℃ / min and held for 1 hour, then heated to 550℃ at 5℃ / min and held for 1 hour. After calcination, the solid was allowed to cool naturally, ground, and sieved to obtain an activated attapulgite sample, denoted as A2.

[0030] Example 3

[0031] A method for preparing attapulgite soil with salt-templating agent synergistic activation includes the following steps: S1. Pretreatment: Similar to step S1 in Example 1, but the concentration of dilute hydrochloric acid is 1.0 mol / L, and the other steps are the same to obtain acid-pretreated attapulgite.

[0032] S2. Preparation of salt-template mixture: Weigh 2.38 g MgCl2·6H2O and dissolve it in 100 mL deionized water to obtain a 0.1 mol / L MgCl2 solution. Add 0.73 g CTAB (concentration 0.02 mol / L) and 0.20 g PEG-1000, and stir to dissolve.

[0033] S3. Mixing and Activation: Weigh 20 g of acid-pretreated attapulgite and mix it with 100 mL of the salt-template mixture (solid-liquid mass ratio 1:5) prepared in step S2. In a 60℃ water bath, stir at 600 r / min for 4 hours, maintaining the pH at 9.0±0.2 with dilute ammonia water during the process.

[0034] S4. Solid-liquid separation and drying: After the reaction is complete, filter directly, wash the solid with deionized water, and dry at 80°C for 12 hours.

[0035] S5. Calcination: The dried solid was heated to 450℃ at a rate of 10℃ / min and calcined for 4 hours. After cooling, the activated attapulgite sample was obtained and designated as A3.

[0036] Comparative Example 1 The difference between this comparative example and Example 1 is that MgCl2 and PEG-1000 are not added in step S2; only a CTAB solution of the same concentration (0.01 mol / L) is prepared for treatment. All other steps are exactly the same as in Example 1. The resulting sample is designated B1.

[0037] Comparative Example 2 The difference between this comparative example and Example 1 is that CTAB and PEG-1000 are not added in step S2; only a MgCl2 solution of the same concentration (0.2 mol / L) is prepared for treatment. All other steps are exactly the same as in Example 1. The resulting sample is designated B2.

[0038] Comparative Example 3 This comparative example is attapulgite treated only with acid, i.e., it only underwent the pretreatment in step S1 of Example 1, without the salt-template agent activation and calcination in steps S2-S5. The resulting sample is designated B3.

[0039] Application Example 1: Adsorption of humic acid in aqueous solution Take seven 250 mL Erlenmeyer flasks and add 100 mL of simulated humic acid (HA) at a concentration of 100 mg / L to each flask. Add 0.05 g (0.5 g / L) of attapulgite samples prepared in Examples 1-3 and Comparative Examples 1-3 to six of the flasks. The seventh Erlenmeyer flask serves as a blank control (no adsorbent added).

[0040] All conical flasks were placed in a constant-temperature shaker and shaken for 120 minutes at 25℃ and 150 r / min. After the predetermined time, samples were taken and immediately filtered through a 0.45 μm filter membrane. The absorbance of the filtrate was measured at 254 nm using a UV-Vis spectrophotometer. The remaining humic acid concentration was calculated based on the standard curve, and the adsorption removal rate was calculated.

[0041] Application Example 2: Adsorption of methylene blue (macromolecular dye) in aqueous solution Prepare a 50 mg / L methylene blue (MB) solution. Take several 100 mL aliquots of this solution and place them in Erlenmeyer flasks. Add different amounts of sample A2 prepared in Example 2 (0.5, 1.0, 2.0, and 5.0 g / L) and sample B3 prepared in Comparative Example 3 (2.0 g / L), respectively. Incubate at 30°C and 200 r / min for 60 minutes with shaking. After adsorption, filter the solution and measure the absorbance of the filtrate at 664 nm. Calculate the adsorption amount and removal rate.

[0042] The following are the data on the removal rate of humic acid by salt-template agent synergistic activation of attapulgite prepared in Examples 1 to 3 and Comparative Examples 1 to 3. The specific test data are shown in Table 1 below: , Table 1 The following are the removal rates of methylene blue by salt-template agent synergistic activation of attapulgite prepared in Example 2 and Comparative Example 3 with different amounts of additives. The specific test data are shown in Table 2 below: , Table 2 Table 1 shows that, under the same dosage, the salt-template synergistic activation of attapulgite prepared in Examples 1-3 of this invention achieved humic acid removal rates of 95.2%, 97.8%, and 92.1%, respectively, significantly higher than those of Comparative Example 1 (68.3%), Comparative Example 2 (58.7%), and the sample of Comparative Example 3 treated only with acid (40.5%). This indicates that the synergistic effect of Mg²⁺, CTAB, and PEG-1000 significantly enhances the adsorption capacity of attapulgite for macromolecular organic humic acid.

[0043] Table 2 shows that when the dosage of A2 is 2 g / L, it exhibits extremely high adsorption efficiency for methylene blue within 60 minutes, with a removal rate as high as 99.5%. Under the same conditions, the removal rate of methylene blue for sample B3 in Comparative Example 3 is only 52.1%. This further confirms the excellent adsorption performance of the activated attapulgite prepared by the method of this invention for macromolecular dyes.

[0044] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, 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. Without further limitations, 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.

[0045] 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 soil synergistically activated by salt and template agent, characterized in that, Includes the following steps: S1. Pretreatment: The raw attapulgite ore is crushed, screened, purified by wet process, and then dried. The purified and dried attapulgite soil is added to 0.5–1.0 mol / L dilute hydrochloric acid at a solid-liquid ratio of 1:10 and stirred at 60℃ for 2 h. After acid treatment, it is centrifuged and washed until neutral and then dried for later use. S2. Preparation of salt-template mixture: Prepare a MgCl2 solution with a concentration of 0.1–0.5 mol / L, and add hexadecyltrimethylammonium bromide (CTAB) to make the CTAB concentration 0.01–0.1 mol / L. Finally, add polyethylene glycol PEG-1000 with a concentration of 1–5 g / L. S3. Mixing and activating: The attapulgite soil pretreated in step S1 is mixed with the salt-template agent mixed solution prepared in step S2 at a solid-liquid mass ratio of 1:5–1:20, and stirred at 40–80℃ for 4–12 h. S4. Solid-liquid separation and drying: The mixture after the reaction in step S3 is subjected to solid-liquid separation, the solid product is collected and dried at 80–120℃; S5. Calcination: The solid dried in step S4 is calcined at 300–550℃ for 2–4 h and then naturally cooled to room temperature to obtain the salt-template agent synergistic activated attapulgite.

2. The preparation method of salt-template agent synergistic activation of attapulgite as described in claim 1, characterized in that: After the mixing and activation in step S3 and before the solid-liquid separation in step S4, an ultrasonic dispersion step is also included: the mixture is subjected to ultrasonic treatment at a frequency of 40–80 kHz for a time of 20–40 min.

3. The preparation method of salt-template agent synergistic activation of attapulgite as described in claim 1, characterized in that: In step S3, the attapulgite pretreated in step S1 and the salt-template agent mixed solution prepared in step S2 are first stirred at 40-60℃ for 2 hours, and then stirred at 60-80℃ for 2-10 hours, while maintaining the pH of the reaction system at 8-9.

4. The preparation method of salt-template agent synergistic activation of attapulgite as described in claim 3, characterized in that: In step S3, the pH of the attapulgite and the prepared salt-template mixture solution is adjusted by adding dilute ammonia water.

5. The method for preparing attapulgite soil with salt-templating agent synergistic activation as described in claim 3 or 4, characterized in that: In step S3, the stirring speed is 200–600 r / min.

6. The method for preparing attapulgite soil with salt-templating agent synergistic activation as described in claim 1, characterized in that: In step S5, the dried solid is first calcined at 300-450℃ for 1 hour, and then calcined at 450-550℃ for 1-3 hours.

7. The method for preparing attapulgite soil with salt-templating agent synergistic activation as described in claim 1, characterized in that: The particle size of the attapulgite after screening in step S1 is no greater than 2 mm. The wet purification process includes crushing the raw ore, adding water to make a suspension, adding a dispersant, and removing impurities by natural sedimentation or centrifugal separation.

8. The application of salt-template agent synergistic activation of attapulgite prepared by any one of claims 1-7 in the adsorption of macromolecular organic matter in aqueous solution.

9. The application of activated attapulgite as described in claim 8 in the adsorption of macromolecular organic matter, characterized in that: The macromolecular organic matter is humic acid or macromolecular dye.

10. The application of activated attapulgite as described in claim 8 or 9 in the adsorption of macromolecular organic matter, characterized in that, Specific application methods include: (1) The salt-template agent is used to synergistically activate attapulgite, which is then added to an aqueous solution containing macromolecular organic matter. The amount of activated attapulgite added is 0.5–5 g / L. (2) At 20–40°C, the aqueous solution is stirred and contacted with the activated attapulgite for 30–120 min; (3) Perform solid-liquid separation to obtain a purified aqueous solution.