Preparation method and application of halloysite nanotube adsorption material with sulfonic groups polymerized on surface

Abstract

The invention discloses a preparation method of a halloysite nanotube adsorption material with sulfonic groups polymerized on the surface, and belongs to the technical field of wastewater treatment materials, the preparation method comprises the following steps: S1, adding 5.0 g of halloysite nanotubes and 5 mL of gamma-methacryloxypropyltrimethoxysilane into 100 mL of toluene; s2, in a magnetic stirrer, condensing and refluxing at 120 DEG C for 10 hours, cooling, filtering, washing with toluene and ethanol for multiple times to remove unreacted KF570, and drying a product in a vacuum drying oven at 60 DEG C for 8 hours to obtain a KH570 modified halloysite nanotube; s3, weighing 1.0 g of HNTs-KH570 as a raw material, dispersing the HNTs-KH570 in 80 mL of distilled water, adding 5.0 g of 2-acrylamide-2-methylpropanesulfonic acid, performing uniform ultrasonic dispersion, and continuously stirring at the temperature of 70 DEG C; and S4, adding 0.15 g of ammonium persulfate into 20 mL of distilled water, and fully stirring to completely dissolve the ammonium persulfate. The adsorption performance of the halloysite nanotube to methylene blue is remarkably improved through sulfonic acid group modification, and the adsorption capacity is improved by 270%.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment materials, and in particular to a preparation method and application of an aluminosilicate nanotube adsorption material with surface-polymerized sulfonic groups. Background Art

[0002] Methylene blue is a typical water-soluble azo cationic dye, which is widely used in the textile, leather, plastic, paper and cosmetic industries. Wastewater is usually discharged into the environment without treatment. Due to its complex aromatic structure, it has strong stability and non-degradability. They may continue to exist in the natural environment and at high concentrations, thus posing a major threat to the environment and human health. Studies have found that excessive intake of dyes causes direct damage to the liver, digestive system and central nervous system. Therefore, it is very necessary to prepare a new adsorbent with strong anti-interference ability, high adsorption capacity and a wide pH range of use.

[0003] Halloysite nanotubes (HNTs) are tubular aluminosilicate clays with a large specific surface area, a nanotubular structure and good biocompatibility; at the same time, due to the different chemical compositions (the outer surface is composed of Si−O, and the inner cavity surface is composed of Al−OH) and charge properties (the inner surface is positively charged and the outer surface is negatively charged) of the inner and outer surfaces of HNTs, halloysite nanotubes have a special size and morphology, formed by two basic building blocks; one is a tetrahedron, and the second is an octahedron. The crystal configuration of halloysite is 1:1 octahedral layer silicate. Structurally, halloysite is tubular and chemically similar to different-sized stacks and platy kaolins. Natural halloysite is a unique and versatile material formed by the surface weathering of aluminosilicate minerals, composed of different proportions of aluminum, silicon, hydrogen and oxygen, with the chemical formula Al4Si4O 10 (OH)·4H2O. HNTs are used in many types of biological and non-biological applications, recycling environmental pollutants, using drugs and various macromolecules as transported goods, storing hydrogen molecules, etc. Halloysite can be used as an adsorption material due to its advantages of large surface area, stable structure, low cost and easy adsorption. HNTs are also very easy to obtain, much cheaper, and there are large reserves in China. Therefore, HNTs may have the potential to replace nanoscale carriers such as carbon nanotubes. However, the adsorption capacity of unmodified raw halloysite is poor, so halloysite nanotubes are modified to improve their adsorption performance for methylene blue. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of an aluminosilicate nanotube adsorption material with surface-polymerized sulfonic groups to solve the problems raised in the background art.

[0005] To achieve the above object, the present invention provides the following technical solution: A preparation method of an attapulgite nanotube adsorption material with surface-polymerized sulfonic acid groups, comprising the following steps: S1: Add 5.0 g of attapulgite nanotubes and 5 mL of γ-methacryloxypropyltrimethoxysilane to 100 mL of toluene; S2: In a magnetic stirrer, reflux with condensation at 120 °C for 10 h, cool, filter, wash with toluene and ethanol multiple times to remove unreacted KF570, and dry the product in a vacuum drying oven at 60 °C for 8 h to obtain KH570-modified attapulgite nanotubes; S3: Weigh 1.0 g of HNTs-KH570 as a raw material and disperse it in 80 mL of distilled water. After adding 5.0 g of 2-acrylamido-2-methylpropanesulfonic acid, ultrasonically disperse it evenly and continuously stir at a temperature of 70 °C; S4: Add 0.15 g of ammonium persulfate to 20 mL of distilled water, stir well to completely dissolve it, gradually add the ammonium persulfate solution to the reaction mixture, and finish dropping within 30 min; S5: React the reactants at 70 °C for 12 h, filter and wash with ethanol, and dry the product in a vacuum at 60 °C for 8 h to finally obtain attapulgite nanotubes modified with sulfonic acid groups with uniform size and dense surface.

[0006] Preferably, in this solution, attapulgite nanotubes (HNTs) are mixed with γ-methacryloxypropyltrimethoxysilane (KH570) and refluxed with condensation in a green solvent for modification, and the green solvent is water.

[0007] Preferably, in this solution, a photoinitiator is used and a radical polymerization reaction is carried out under ultraviolet light irradiation, and the ultraviolet light wavelength range is 365 nm to 405 nm.

[0008] Preferably, in this solution, sulfonic acid groups are introduced by atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer controlled / living polymerization technology in S4.

[0009] Preferably, the polymerization conditions include but are not limited to using a halide as an activation end, the ligand is N,N,N',N'',N''-pentamethyldiethylenetriamine, the metal catalyst is copper bromide (CuBr), and the pH value of the reaction medium is maintained at 7.

[0010] Preferably, the method further includes compounding HNTs-SO3H with its functionalized nanoparticles to form a multifunctional composite adsorbent, and the functionalized nanoparticles include but are not limited to magnetic nanoparticles Fe3O4 and metal-organic frameworks MOFs.

[0011] Preferably, in this solution, the method is for gas-phase adsorption, including but not limited to the removal of volatile organic compounds and the capture of heavy metal vapors in the air.

[0012] Preferably, in this solution, soft templates or hard templates are also used in the method to guide the spatial arrangement of sulfonic acid groups to form an ordered three-dimensional network structure.

[0013] Preferably, in this solution, temperature-sensitive and pH-sensitive monomers are introduced into the method to make HNTs-SO3H an intelligent material that can automatically adjust its adsorption behavior according to changes in environmental conditions.

[0014] Application of the adsorbent material prepared by a method for preparing an aluminosilicate nanotube adsorbent material with surface-polymerized sulfonic acid groups in the treatment of industrial wastewater Compared with the prior art, the technical effects and advantages of the present invention: For the method for preparing the aluminosilicate nanotube adsorbent material with surface-polymerized sulfonic acid groups and its application, the modification of sulfonic acid groups significantly improves the adsorption performance of aluminosilicate nanotubes for methylene blue, and the adsorption capacity is increased by 270%. HNTs-SO3H is used for the adsorption of methylene blue, and the adsorption effect is good in the pH range of 5-11, indicating that the new material has a wide pH range for use. HNTs-SO3H has strong anti-interference ability, and metal ions such as ionic strength, Zn 2+ , Pb 2+ , Fe 2+ , Cu 2+ etc. have no influence on the adsorption of methylene blue.

[0015] This method uses surface polymerization to introduce a large number of sulfonic acid group active adsorption sites on the surface of aluminosilicate nanotubes, thereby significantly improving its adsorption capacity for methylene blue. This new adsorbent material solves the problems of low adsorption capacity and susceptibility to environmental interference of existing materials, and expands the pH range for material adsorption. At room temperature, the maximum equilibrium adsorption capacity is 397.8 mg / g; it has very good adsorption effect on methylene blue in the pH range of 5-11; it has good anti-interference ability, and metal ions such as ionic strength, Zn 2+ , Pb 2+ , Fe 2+ , Cu 2+ etc. have no influence on the adsorption of methylene blue. Again, this synthesis route is relatively simple and has strong practicability.

[0016] Using water as the sole solvent avoids the environmental pollution problems caused by traditional organic solvents, reduces the emission of harmful substances, and conforms to the current development trend of green environmental protection. A photoinitiator (such as a copper(I) iodide complex) is used instead of a traditional thermal initiator (such as ammonium persulfate APS) to carry out a free radical polymerization reaction under ultraviolet light irradiation. This method not only improves the selectivity and efficiency of the reaction, but also significantly reduces the generation of by-products and simplifies the subsequent purification steps. By precisely controlling the light irradiation conditions (wavelength range from 365 nm to 405 nm), the polymerization process can be more accurately regulated, thus obtaining higher yields and higher quality products.

[0017] Using water as the solvent and the photoinitiator not only reduces environmental pollution, but also unexpectedly enhances the thermal stability and chemical stability of the material. This is because the photoinitiated reaction usually occurs at a lower temperature, avoiding the destruction of the material structure at high temperatures; at the same time, the polymerization reaction under aqueous conditions may promote a stronger binding force between the surface of HNTs and sulfonic acid groups, thus improving the overall stability of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is the synthesis route diagram of HNTs-SO3H of the present invention; Figure 2 It is the SEM diagram of the present invention; Figure 3 It is the infrared spectrum diagram of HNTs, HNTs-KH570 and HNTs-SO3 of the present invention; Figure 4 It is the XRD diagram of the present invention; Figure 5 It is the thermogravimetric analysis diagram of the present invention; Figure 6 It is the adsorption situation diagram of methylene blue before and after the modification of HNTs of the present invention; Figure 7 It is the analysis diagram of the influence of pH on adsorption of the present invention; Figure 8 It is the analysis diagram of the influence of oscillation time on adsorption of the present invention; Figure 9Curves of different kinetic models of the present invention: (a) Nonlinear fitting of pseudo-first-order kinetic model; (b) Nonlinear fitting of pseudo-second-order kinetic model; (c) Elovich model; (d) Linear fitting (intraparticle diffusion model) analysis diagram. Figure 10 Isothermal adsorption line diagram of the present invention. Figure 11 Curves of four adsorption isotherm models of the present invention: (a) D-R model; (b) Freundlich model; (c) Langmuir model; (d) Temkin model diagram. Figure 12 Analysis diagram of the effects of ionic strength and metal ions on methylene blue of the present invention. Figure 13 Flow chart of the preparation method of a halloysite nanotube adsorbent material with surface-polymerized sulfonic acid groups of the present invention. Detailed implementation mode

[0020] In the following description, a large number of specific details are given to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some well-known technical features in the art are not described.

[0021] Unless otherwise defined, the directions such as up, down, left, right, front, back, inside and outside involved in this article are based on the up, down, left, right, front, back, inside and outside in the figures shown in the present invention, and are hereby explained together.

[0022] This embodiment provides a preparation method of a halloysite nanotube adsorbent material with surface-polymerized sulfonic acid groups as shown in Figures 1 to 13 and includes the following steps: S1: Add 5.0 g of halloysite nanotubes (HNTs) and 5 mL of γ-methacryloxypropyltrimethoxysilane (KH570) to 100 mL of toluene. S2: In a magnetic stirrer, carry out condensation reflux at 120 °C for 10 h, cool, filter, wash with toluene and ethanol multiple times to remove unreacted KF570, and dry the product in a vacuum drying oven at 60 °C for 8 h to obtain KH570-modified halloysite nanotubes (HNTs-KH570). S3: Weigh 1.0 g of HNTs-KH570 as a raw material and disperse it in 80 mL of distilled water. After adding 5.0 g of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), ultrasonically disperse it evenly, and continuously stir at a temperature of 70 °C. S4: Add 0.15 g of ammonium persulfate (APS) into 20 mL of distilled water, stir well to completely dissolve it, gradually add the ammonium persulfate solution into the reaction mixture, and finish the dropping within 30 min; S5: React the reactants at 70 °C for 12 h, filter and wash with ethanol, then vacuum dry the product at 60 °C for 8 h to finally obtain halloysite nanotubes modified with sulfonic acid groups (HNTs-SO3H) with uniform size and dense surface; In this example, halloysite nanotubes (HNTs) were mixed with γ-methacryloxypropyltrimethoxysilane (KH570) and condensed and refluxed in a green solvent for modification, and the green solvent was water.

[0023] In this example, a photoinitiator was used instead of a traditional thermal initiator, such as ammonium persulfate (APS), and a free radical polymerization reaction was carried out under ultraviolet light irradiation, and the ultraviolet light wavelength range was 365 nm to 405 nm.

[0024] In this example, sulfonic acid groups were introduced by controlled / living polymerization techniques such as atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) in S4.

[0025] In this example, the polymerization conditions include but are not limited to using a halide as the activation end, the ligand is N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA), the metal catalyst is copper bromide (CuBr), and the pH value of the reaction medium is maintained at about 7.

[0026] In this example, the method further includes compounding HNTs-SO3H with its functionalized nanoparticles to form a multifunctional composite adsorbent, and the functionalized nanoparticles include but are not limited to magnetic nanoparticles Fe3O4 and metal-organic frameworks MOFs.

[0027] In this example, the method is for gas phase adsorption, including but not limited to the removal of volatile organic compounds (VOCs) and the capture of heavy metal vapors in the air.

[0028] In this example, soft templates (such as micelles, emulsion droplets) or hard templates (such as mesoporous silica) were also used to guide the spatial arrangement of sulfonic acid groups to form an ordered three-dimensional network structure, and the three-dimensional network structure significantly improved the mass transfer efficiency, accelerated the adsorption rate, and achieved selective adsorption.

[0029] In this embodiment, temperature-sensitive and pH-sensitive monomers are introduced into the method, making HNTs-SO3H an intelligent material that can automatically adjust its adsorption behavior according to environmental conditions. The intelligent response characteristics are applicable to the efficient capture and release of pollutants in a dynamic environment.

[0030] Application of an adsorption material prepared by a method for preparing an aluminosilicate nanotube adsorption material with surface-polymerized sulfonic acid groups in the treatment of industrial wastewater.

[0031] In this embodiment, as Figure 2 (a), it can be seen that the original structure of the aluminosilicate nanotubes is tubular. Comparing Figure 2 (b), it is easy to know that the diameter of the HNTs-SO3H material after surface polymerization of sulfonic acid groups on the aluminosilicate nanotubes becomes significantly larger, indicating that new substances are formed on the surface of HNTs.

[0032] In this embodiment, as Figure 3 shown, a strong absorption band appears near 1031.7 cm-¹ in the infrared spectrum of HNTs. This absorption band corresponds to the stretching vibration of Si-O and is a typical feature of the silicate structure in the aluminosilicate nanotubes (HNTs). In addition, the absorption peaks at 3696.9 cm-¹ and 3619.8 cm-¹ represent the O-H stretching vibration of the hydroxyl groups on the surface of HNTs. These hydroxyl groups are important functional groups on the surface of HNTs and have an important impact on their adsorption performance. Infrared spectrum of HNTs-SO3H. Compared with HNTs, a new absorption peak appears at 1088.7 cm-¹ in the spectrum of HNTs-SO3H. This absorption peak corresponds to the S-O stretching vibration peak of the sulfonic acid group and is direct evidence of the successful introduction of the sulfonic acid group onto the surface of HNTs. The introduction of the sulfonic acid group not only changes the surface properties of HNTs but also endows it with new functions and increases the active adsorption sites.

[0033] In this embodiment, Figure 4 are the X-ray diffraction patterns of HNTs, HNTs-KH570, and HNTs-SO3H. Under the modification of the sulfonic acid group, the crystal structure of HNTs does not change significantly.

[0034] In this embodiment, as Figure 5 shown by the weight loss curve, before and after the modification of the aluminosilicate nanotubes, the weight loss temperature is concentrated at 300-500 °C. The reason is that the dehydration process of the hydroxyl groups on the HNTs tube wall is the loss of chemically bound water. The weight loss of HNTs is 0.97%. In addition, HNTs-SO3H also shows another weight loss at 50-200 °C due to the decomposition of the sulfonic acid group. The results show that the aluminosilicate nanotubes are successfully modified by the sulfonic acid group.

[0035] In this example, the prepared novel adsorbent material HNTs-SO3H was used for the adsorption of methylene blue: 1. Halloysite nanotubes before and after modification were used for the adsorption of methylene blue. As Figure 6 shown, the adsorption capacity before modification was 48.6 mg / g. After surface polymerization of sulfonic acid groups, the adsorption capacity increased to 180.2 mg / g, with a 270% increase in the adsorption capacity. The main reason is that the modification of sulfonic acid groups increased the active sites adsorbed on the surface of halloysite nanotubes, significantly improving their adsorption ability for methylene blue.

[0036] 2. Influence of solution pH on the adsorption effect. Add 10 mg of HNTs-SO3H and 6 mg of methylene blue to a 40 mL centrifuge tube, and make up the volume to 20 mL with distilled water of different pH values (pH = 3 - 12). Shake and react at room temperature for 4 h, filter, and measure the absorbance of the filtrate at a wavelength of 257 nm. The results are as Figure 7 shown. When the solution pH is 5 - 11, the adsorption capacity of HNTs-SO3H for methylene blue is relatively high, indicating that the material can be used in a wide pH range for the adsorption of methylene blue.

[0037] 3. Influence of oscillation time on the adsorption effect. Take 20 mL of a methylene blue solution with a concentration of 300 mg / L at pH 10, add 10 mg of the HNTs-SO3H adsorbent material respectively. After ultrasonic dispersion for 5 min, change the oscillation time (10 min, 20 min, 30 min, 40 min, 1 h, 2 h, 4 h, 8 h), filter, and take the filtrate to measure the absorbance at 257 nm. The results are as Figure 8 shown. The adsorption ability gradually increases with the extension of time and reaches an equilibrium state at 240 min.

[0038] 4. Adsorption kinetics. To further study the adsorption kinetics, different kinetic models were used to fit the data respectively. As Figure 9 shown, the best fitting result for the adsorption of methylene blue by HNTs-SO3H is the pseudo-second-order kinetic model, and its linear correlation coefficient R2 is 0.99994. This indicates that the adsorption of methylene blue by the HNTs-SO3H material can be more accurately explained by the pseudo-second-order kinetic model.

[0039] 5. Isothermal adsorption curve and adsorption thermodynamics. Figure 10Adsorption performance of HNTs-SO3H for methylene blue at different temperatures. The study found that under the experimental conditions of pH = 10, using 10 mg of adsorbent, and an adsorption duration of 4 hours, the higher the initial concentration of methylene blue, the better the adsorption effect. In addition, the adsorption efficiency follows the temperature order: the highest at 25 °C, followed by 35 °C, and the lowest at 45 °C. This indicates that as the temperature increases, the adsorption effect gradually weakens, suggesting that this adsorption process releases heat and high temperature is not conducive to the adsorption process. At room temperature, the maximum equilibrium adsorption capacity is 397.8 mg / g.

[0040] The Langmuir model, Freundlich model, Temkin model, and D-R model were used to fit the thermodynamic data, and the fitting results are as Figure 11 shown. At all temperatures (25 °C, 35 °C, 45 °C), the R² value of the Langmuir equation is less than that of the Freundlich equation. This indicates that the Freundlich model can better describe the adsorption behavior of HNTs-SO3H for methylene blue. The Freundlich model is usually used to describe the adsorption on heterogeneous surfaces, suggesting that there may be multiple adsorption sites on the surface of HNTs-SO3H. The R² value of the Temkin equation is generally greater than that of the D-R equation. This means that the Temkin model is more accurate in describing the adsorption of HNTs-SO3H for methylene blue. The Temkin model takes into account the interaction between the adsorbent and the adsorbate, which may be of great significance for understanding the adsorption mechanism.

[0041] 6. Evaluation of adsorption interference. Sodium chloride solutions with concentrations of 0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 mol / L and metal ions of Pb 2+ , Cu 2+ , Zn 2+ , Fe 2+ were added respectively during the adsorption of methylene blue. As Figure 12 shown, the experiment found that the ionic strength (NaCl concentration), Zn 2+ , Pb 2+ , Fe 2+ , Cu 2+ and other metal ions have no effect on the adsorption of methylene blue, indicating that this new material has good anti-interference ability.

[0042] In this embodiment, when using green solvents and environmentally friendly initiators, water, which is harmless to the environment and easy to handle, is selected as the solvent to avoid the environmental pollution problems caused by traditional organic solvents. The steps are as follows: b) Preparation of materials: Mix halloysite nanotubes (HNTs) with γ-methacryloxypropyltrimethoxysilane (KH570), and carry out condensation reflux in water for modification to obtain KH570-modified halloysite nanotubes (HNTs-KH570).

[0043] c) Addition of photoinitiator: Add copper(I) iodide complex or other suitable photoinitiator to the HNTs-KH570 dispersion, and ultrasonically disperse it evenly.

[0044] d) Ultraviolet light irradiation: Irradiate the above mixture with ultraviolet light, preferably in the wavelength range of 365 nm to 405 nm. After the photoinitiator absorbs the ultraviolet light energy, it decomposes to generate free radicals, initiating the polymerization reaction of AMPS monomers, and finally forming a sulfonic acid group modification layer on the surface of HNTs.

[0045] e) Product separation and purification: Remove unreacted substances by filtration and washing, and then dry in vacuum at 60 °C for 8 hours to obtain the target product HNTs-SO3H.

[0046] In this example, the specific steps for the change in the introduction method of sulfonic acid groups are as follows: a) Preparation of the activation end: First, introduce halogen atoms (such as bromine) on the surface of HNTs by chemical means as the activation end for subsequent polymerization reactions.

[0047] b) Ligand selection: Select N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA) as the ligand, which can stabilize the metal catalyst and regulate the polymerization reaction rate.

[0048] c) Metal catalyst: Use copper(II) bromide (CuBr) as the metal catalyst, and keep the pH value of the catalytic system around 7 to ensure mild and stable reaction conditions.

[0049] d) Initiating polymerization: Under the above conditions, gradually add the initiator to the aqueous solution containing HNTs-KH570 and AMPS to initiate the ATRP or RAFT polymerization process. During this process, the halogen activation end can undergo continuous addition-fragmentation cycles with AMPS monomers, thereby achieving highly controlled polymerization degrees.

[0050] e) Product treatment: After the reaction is completed, separate, wash, and dry according to the conventional method to obtain HNTs-SO3H with a uniform sulfonic acid group distribution.

[0051] In this example, the specific steps for combining functional nanomaterials are as follows: a) Pretreatment of nanoparticles: First, prepare Fe3O4 nanoparticles or synthesize MOF materials, and carry out necessary surface modification on them for subsequent combination.

[0052] b) Hybrid dispersion: Disperse the treated nanoparticles together with HNTs-SO3H in a suitable medium, such as water or a low-concentration alcohol solution.

[0053] c) Physical or chemical bonding: Closely bond the two materials through physical blending or chemical bonding. For Fe3O4, it can be achieved through electrostatic interaction or self-assembly assisted by surfactants; for MOFs, it may involve coordination bonds or other types of chemical linkages.

[0054] d) Optimize the structure: Adjust the proportion and arrangement of the nanoparticles to maximize the functional properties of the composite material, such as increasing the specific surface area, improving conductivity, or endowing magnetic response ability.

[0055] e) Application testing: Evaluate the performance of the composite material to verify whether it has achieved the expected functional improvement effects, such as enhanced adsorption capacity, better mechanical strength, etc.

[0056] In this embodiment, the development of gas-phase adsorption applications is applicable to applications such as the removal of volatile organic compounds (VOCs) and the capture of heavy metal vapors in the air. The specific steps are as follows: a) Adsorbent morphology design: Prepare HNTs-SO3H into a form suitable for gas contact, such as powder, fiber, or membrane structure.

[0057] b) Gas flow system: Construct a device that allows the gas to be treated to pass through the adsorption bed, ensuring uniform gas flow distribution and sufficient contact with the adsorbent.

[0058] c) Adsorption mechanism: Utilize the physical and chemical adsorption between the abundant sulfonic acid groups on the surface of HNTs-SO3H and VOCs molecules, as well as the complexes formed with heavy metal ions, to achieve efficient capture.

[0059] d) Regeneration and reuse: Study how to restore the activity of the adsorbent through heating, pressure reduction desorption, or other methods to ensure its multiple cyclic use.

[0060] e) Practical case analysis: Conduct laboratory-scale experiments and on-site pilot projects to collect data to prove the effectiveness and economic feasibility of the new technology under different working conditions.

[0061] In this embodiment, the specific steps for constructing a three-dimensional network structure using the template-directed method are as follows: a) Select template materials: Select appropriate template materials according to the required structural characteristics, such as polystyrene microspheres, SiO2 nanoparticles, etc.

[0062] b) Template assembly: Mix the template material with the HNTs-SO3H precursor solution through self-assembly or other methods to form an ordered arrangement.

[0063] c) Polymerization reaction: Conduct the reaction for introducing sulfonic acid groups in the presence of the template to ensure the directional growth of sulfonic acid groups along the template surface.

[0064] d) Template removal: After the reaction is completed, remove the template by means such as solvent extraction and high-temperature calcination, leaving behind a three-dimensional network structure with a specific morphology.

[0065] e) Performance evaluation: Measure indicators such as the specific surface area, pore size distribution, and mechanical properties of the obtained material to confirm that it has excellent adsorption performance and selectivity.

[0066] In this example, the specific steps for the design of the intelligent responsive adsorbent material are as follows: a) Selection of responsive monomers: Screen out monomers that can change their conformation or solubility under specific conditions, such as thermosensitive poly(N-isopropylacrylamide) (PNIPAM), pH-sensitive poly(methacrylic acid) (PMAA), etc.

[0067] b) Copolymerization reaction: Let the responsive monomers and AMPS participate in the polymerization reaction together, so that the final product contains both sulfonic acid groups and responsive side chains.

[0068] c) Response mechanism: When the environmental temperature rises, the PNIPAM chain changes from hydrophilic to hydrophobic, resulting in a decrease in the adsorption capacity; vice versa, it increases. Similarly, PMAA will carry a negative charge and repel anionic dyes under acidic conditions, and lose the charge and re-adsorb under alkaline conditions.

[0069] d) Application scenarios: This intelligent responsive characteristic is particularly suitable for use in sewage treatment plants, where it can automatically adjust the working state according to the fluctuations in the influent water quality to ensure stable and reliable treatment effects.

[0070] e) Long-term stability test: Study whether the intelligent material can maintain good responsive characteristics and adsorption performance under repeatedly changing environments to ensure its practical value.

[0071] It should be noted that, in this document, relational terms such as "one" and "two" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising a..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

[0072] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of halloysite nanotube adsorption material with surface polymerized sulfonic groups, characterized in that, It includes the following steps: S1: Add 5.0 g of halloysite nanotubes and 5 mL of γ-methacryloxypropyltrimethoxysilane into 100 mL of toluene; S2: In a magnetic stirrer, carry out condensation reflux at 120 °C for 10 h, cool, filter, wash with toluene and ethanol multiple times to remove unreacted KF570, and dry the product in a vacuum drying oven at 60 °C for 8 h to obtain KH570-modified halloysite nanotubes; S3: Weigh 1.0 g of HNTs-KH570 as raw material and disperse it in 80 mL of distilled water. After adding 5.0 g of 2-acrylamido-2-methylpropanesulfonic acid, ultrasonically disperse it evenly and continuously stir at a temperature of 70 °C; S4: Add 0.15 g of ammonium persulfate into 20 mL of distilled water, stir well to completely dissolve it, gradually add the ammonium persulfate solution into the reaction mixture, and finish dropping within 30 min; S5: React the reactants at 70 °C for 12 h, filter and wash with ethanol, and dry the product in vacuum at 60 °C for 8 h to finally obtain halloysite nanotubes modified with sulfonic acid groups with uniform size and dense surface.

2. The preparation method of a halloysite nanotube adsorption material with surface polymerized sulfonic groups according to claim 1, wherein: Mix halloysite nanotubes (HNTs) with γ-methacryloxypropyltrimethoxysilane (KH570) and carry out modification by condensation reflux in a green solvent, and the green solvent is water.

3. The preparation method of a halloysite nanotube adsorption material with surface polymerized sulfonic acid groups according to claim 2, wherein: Use a photoinitiator and carry out a free radical polymerization reaction under ultraviolet light irradiation, and the ultraviolet light wavelength range is 365 nm to 405 nm.

4. The preparation method of a halloysite nanotube adsorption material with surface polymerized sulfonic groups according to claim 3, characterized in that: In S4, introduce sulfonic acid groups through atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer controlled / living polymerization technology.

5. The preparation method of a halloysite nanotube adsorption material with surface polymerized sulfonic acid groups according to claim 4, characterized in that: The polymerization conditions include but are not limited to using a halide as the activation end, the ligand is N,N,N',N'',N''-pentamethyldiethylenetriamine, the metal catalyst is copper bromide (CuBr), and the pH value of the reaction medium is maintained at 7.

6. The preparation method of a halloysite nanotube adsorption material with surface polymerized sulfonic groups according to claim 5, characterized in that: The method also includes compounding HNTs-SO3H with its functionalized nanoparticles to form a multifunctional composite adsorbent, and the functionalized nanoparticles include but are not limited to magnetic nanoparticles Fe3O4 and metal-organic frameworks MOFs.

7. The preparation method of a halloysite nanotube adsorption material with surface polymerized sulfonic groups according to claim 6, characterized in that: In the method, it is used for gas phase adsorption, including but not limited to the removal of volatile organic compounds and the capture of heavy metal vapors in the air.

8. The method for preparing a halloysite nanotube adsorption material with surface polymerized sulfonic acid groups according to claim 7, characterized in that: In the method, a soft template or a hard template is also used to guide the spatial arrangement of sulfonic acid groups to form an ordered three-dimensional network structure.

9. The preparation method of the halloysite nanotube adsorption material with surface polymerized sulfonic acid groups according to claim 8, characterized in that: In the method, temperature-sensitive and pH-sensitive monomers are introduced to make HNTs-SO3H an intelligent material that can automatically adjust its adsorption behavior according to environmental conditions.

10. Application of the adsorbent prepared by the preparation method of an aluminosilicate nanotube adsorbent with surface-polymerized sulfonic acid groups according to any one of claims 1-9 in the treatment of industrial wastewater.

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