Preparation method and application of a multifunctional super-hydrophobic biomass aerogel with magnetic response
By introducing CMIL-101 and PDMS into chitosan aerogel, a magnetically responsive multifunctional superhydrophobic biomass aerogel was prepared, which solved the problem of reduced adsorption capacity caused by the hydrophilicity of chitosan aerogel. It achieved efficient oil-water separation and microplastic removal, and has high specific surface area, low density, open pore structure and excellent mechanical properties, making it suitable for multifunctional water pollution treatment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LIAONING UNIVERSITY
- Filing Date
- 2024-10-24
- Publication Date
- 2026-05-19
AI Technical Summary
Existing chitosan aerogel materials exhibit hydrophilicity in oil-water separation and microplastic adsorption, resulting in reduced adsorption capacity for microplastics. Furthermore, existing materials have limited functionality, making it difficult to achieve efficient oil-water separation and microplastic removal.
Multifunctional aerogels were prepared using freeze-drying technology. By introducing CMIL-101 and hydrophobic material PDMS into chitosan aerogels, magnetic and hydrophobic properties were imparted to them, forming magnetically responsive multifunctional superhydrophobic biomass aerogels PDMS@CMIL-101/CS.
It achieves efficient adsorption of microplastics and oil, and has high specific surface area, low density, open pore structure and excellent mechanical properties. It can maintain high adsorption efficiency in harsh environments, and simplifies the separation process through magnetic response and photothermal conversion, thereby reducing production costs.
Smart Images
Figure CN119186420B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of superhydrophobic materials technology, specifically relating to a method for preparing and applying a magnetically responsive multifunctional superhydrophobic biomass aerogel. Background Technology
[0002] Oily wastewater is a type of wastewater generated during processes such as oil extraction, refining, and petrochemical production. Furthermore, oil spills from ships inevitably lead to the presence of oil in freshwater resources. This wastewater not only damages the ecological environment but also affects human health because its toxic components can evaporate into the air and be absorbed through the skin and respiratory system. Additionally, untreated wastewater contains the SARS-CoV-2 virus, and the flow of harmful water provides a pathway for its spread. Direct discharge of oily wastewater exacerbates the turbidity of natural water, causing severe impacts on the production and living environment. Furthermore, microplastics (MPs) are ubiquitous in aquatic and terrestrial environments, causing ecological hazards, bioaccumulation, water pollution, and disruption of the water cycle. Although various filtration and adsorption materials have been developed to purify wastewater, many existing solutions are limited by their single function, targeting only specific types of wastewater. There is an urgent need for innovative, economical, and environmentally friendly multifunctional materials to achieve oil-water separation and the removal of emerging pollutants.
[0003] In recent years, superhydrophobic materials have gained widespread popularity due to their excellent oil absorption selectivity and waterproof properties, making them ideal materials for separating oil-water mixtures and emulsions. Porous materials with excellent oil-water separation efficiency, such as aerogels, porous membranes, and sponges, have attracted extensive attention, especially chitosan aerogels. Chitosan molecules contain a large number of active groups such as amino and hydroxyl groups, which can provide many active sites for chemical reactions. In addition, chitosan is widely available in nature, inexpensive, biocompatible, and biodegradable, making it a good framework material. Therefore, chitosan aerogels possess advantages such as high specific surface area, low density, high porosity, open cell structure, good mechanical properties, and low cost, enabling them to be applied to oil-water separation and MPs adsorption. However, pure chitosan aerogels exhibit hydrophilicity, meaning they will simultaneously adsorb water and MPs, thus greatly reducing their adsorption capacity for MPs and even destroying their mechanical behavior. Therefore, we need to modify pure chitosan aerogel to selectively absorb oil or water, thereby achieving oil-water separation. It is also expected to achieve better absorption performance and higher recyclability when removing MPs, thus realizing a multifunctional application of MP adsorption and oil-water separation. Summary of the Invention
[0004] This invention uses freeze-drying technology to prepare a multifunctional aerogel. Chitosan is used as a carrier to support CMIL-101 and give it magnetism. Hydrophobic materials are used for hydrophobic treatment. The resulting aerogel has a high adsorption capacity for MPs and oil, with an adsorption efficiency close to 100%.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] A method for preparing a magnetically responsive multifunctional superhydrophobic biomass aerogel includes the following steps:
[0007] 1) Dissolve ferric chloride hexahydrate in N,N-dimethylformamide to form solution A, dissolve terephthalic acid in solution A to form solution B, perform hydrothermal reaction, centrifuge and wash, dry, calcine to obtain CMIL-101;
[0008] 2) Add CMIL-101 to deionized water, add chitosan CS and acetic acid, stir vigorously to form a high-viscosity chitosan hydrogel, freeze dry to obtain CMIL-101 / CS aerogel.
[0009] 3) Dissolve the hydrophobic material and curing agent in an organic solvent and stir to obtain a uniform suspension. Immerse the CMIL-101 / CS aerogel in the suspension and then vacuum dry the mixture to obtain magnetically responsive multifunctional superhydrophobic chitosan aerogel PDMS@CMIL-101 / CS.
[0010] Furthermore, in the above preparation method, in step 1), the molar ratio of ferric chloride hexahydrate to terephthalic acid is 2:1.
[0011] Furthermore, in the above preparation method, step 1), the hydrothermal reaction is carried out at 110°C for 20 hours.
[0012] Furthermore, in the above preparation method, step 1), the calcination condition is calcination at 500°C for 2 hours.
[0013] Furthermore, in the above preparation method, in step 2), the chitosan CS:CMIL-101 ratio is 5 to 10:1 by mass.
[0014] Preferably, in the above preparation method, in step 2), the chitosan CS:CMIL-101 mass ratio is 10:1.
[0015] Furthermore, in the above preparation method, step 3), the hydrophobic material is selected from stearic acid, lauric acid, PFTEOS, or polydimethylsiloxane.
[0016] Preferably, in the above preparation method, in step 3), the hydrophobic material is polydimethylsiloxane.
[0017] Furthermore, in the above preparation method, step 3), the curing agent is diphenylcarbamate.
[0018] Furthermore, in the above preparation method, step 3), the organic solvent is n-hexane.
[0019] The application of the magnetically responsive multifunctional superhydrophobic biomass aerogel PDMS@CMIL-101 / CS prepared by any of the above preparation methods as an adsorbent for the removal of organic pollutants.
[0020] Further, the above application is carried out as follows: take an aqueous solution containing organic pollutants, adjust the solution to neutral, then add magnetically responsive multifunctional superhydrophobic biomass aerogel PDMS@CMIL-101 / CS, shake to adsorb, and then separate using a magnet.
[0021] Preferably, in the above application method, the pH of the aqueous solution containing organic pollutants is adjusted to 7.
[0022] Furthermore, in the above-described application, the organic pollutant is microplastic organic matter.
[0023] Preferably, in the above-described application, the microplastic organic material is polystyrene microplastic.
[0024] Application of the magnetically responsive multifunctional superhydrophobic biomass aerogel PDMS@CMIL-101 / CS prepared by any of the above preparation methods as an adsorbent in oil-water separation.
[0025] Further, the above application is carried out by the following method: magnetically responsive superhydrophobic chitosan aerogel PDMS@CMIL-101 / CS is added to an oil-water mixture and allowed to stand for adsorption.
[0026] Furthermore, in the above applications, the oil includes n-hexane, n-pentane, dichloromethane, ethyl acetate, N,N-dimethylformamide, chloroform, engine oil, peanut oil, or olive oil.
[0027] The beneficial effects of this invention are:
[0028] 1. Compared with pure chitosan aerogel, the PDMS@CMIL-101 / CS of the present invention has a higher specific surface area, lower density, higher porosity, more open pore structure and better mechanical properties, providing a new strategy for water pollution control.
[0029] 2. The PDMS@CMIL-101 / CS of the present invention can simultaneously adsorb MPs and separate oil and water, and also has a good removal effect on other novel pollutants, and still has excellent adsorption effect in harsh environments such as strong acids and strong salts.
[0030] 3. The PDMS@CMIL-101 / CS of this invention possesses excellent magnetic and photothermal conversion properties, enabling oil to be autonomously adsorbed under a magnetic field and promoting the treatment of high-viscosity oils, thus simplifying the separation process. This work contributes to the development of multifunctional bio-based adsorbents for effective water remediation.
[0031] 4. The preparation method of this invention requires no expensive reagents or equipment, nor does it require harsh experimental conditions, greatly reducing production costs. The synthesized aerogel possesses magnetic response characteristics, enabling efficient and controllable oil-water separation. These materials, with their high specific surface area, low density, high porosity, open pore structure, and excellent mechanical properties, provide a new strategy for water pollution control and are of great significance for promoting the development of oil-water separation technology and ecological environmental protection. Attached Figure Description
[0032] Figure 1 This is a schematic diagram of the synthesis of PDMS@CMIL-101 / CS aerogel.
[0033] Figure 2 These are photos of PDMS@CMIL-101 / CS aerogel on pine branches (a) and flower cores (b).
[0034] Figure 3 This is the FT-IR spectrum of PDMS@CMIL-101 / CS aerogel.
[0035] Figure 4 This relates to the effect of adding hydrophobic materials on microplastic removal.
[0036] Figure 5 These are stability test diagrams for PDMS@CMIL-101 / CS aerogel. (a) shows the mechanical stability measured by sandpaper friction, (b) shows the light oil separation cycle stability, and (c) shows the heavy oil separation cycle stability.
[0037] Figure 6 The images are (a) a photograph of a water droplet on PDMS@CMIL-101 / CS, (b) a photograph of PDMS@CMIL-101 / CS exhibiting perfect waterproof performance under water flux, and (c) a photograph of the silver mirror phenomenon of PDMS@CMIL-101 / CS immersed in water.
[0038] Figure 7 This is a graph showing the absorption capacity of PDMS@CMIL-101 / CS in different organic solvents.
[0039] Figure 8 These are photographs of the absorption processes of dichloromethane (a) and n-hexane (b) by PDMS@CMIL-101 / CS.
[0040] Figure 9 These are photos of dynamic oil-water separation (pump separation) of oils with different densities using PDMS@CMIL-101 / CS.
[0041] Figure 10 This is an optical image of the clockwise magnetically driven spiral oil suction motion of the PDMS@CMIL-101 / CS.
[0042] Figure 11 These are photographs of the wetting behavior of high viscosity oil on the top of the PDMS@CMIL-101 / CS surface under no light (a) and light (b) conditions.
[0043] Figure 12 These are photos of the hydrophobicity of PDMS@CMIL-101 / CS under different harsh environments. Detailed Implementation
[0044] Example 1: Magnetically responsive multifunctional superhydrophobic biomass aerogel (PDMS@CMIL-101 / CS)
[0045] (I) The preparation method is as follows:
[0046] The synthetic route of PDMS@CMIL-101 / CS is as follows: Figure 1 .
[0047] 1) Preparation of CMIL-101:
[0048] 4.9 mmol of ferric chloride hexahydrate was dissolved in 30 mL of N,N-dimethylformamide to form solution A, and 2.48 mmol of terephthalic acid was dissolved in solution A to form solution B. The mixture was hydrothermally reacted at 110 °C for 20 h. The precipitate was collected by centrifugation, washed, and dried. The resulting product was calcined at 500 °C for 2 h to obtain CMIL-101.
[0049] 2) Preparation of CMIL-101 / CS aerogel:
[0050] Add 0.2g of CMIL-101 to 20mL of deionized water, then add 2.0g of chitosan (CS) to the above mixed solution, slowly add 0.8mL of acetic acid solution, stir vigorously to form a high-viscosity chitosan hydrogel, freeze-dry for 24 hours to obtain CMIL-101 / CS aerogel.
[0051] 3) Preparation of PDMS@CMIL-101 / CS:
[0052] 0.847 g of PDMS (polydimethylsiloxane) and 0.0847 g of curing agent (butyl diphenylcarbamate) were dissolved in 50 mL of n-hexane and stirred for 5 min to obtain a homogeneous suspension. The CMIL-101 / CS aerogel was immersed in the suspension and vacuum dried to obtain magnetically responsive superhydrophobic chitosan aerogel PDMS@CMIL-101 / CS.
[0053] (II) Testing
[0054] PDMS@CMIL-101 / CS aerogel is ultralight, like Figure 2 As shown, aerogels can be placed on relatively light substrates (such as flower centers and pine branches) without deformation. Furthermore, the simple and controllable method ensures that aerogels can be easily designed and manufactured into desired shapes (such as cubes, solid polygons, and other complex three-dimensional shapes) for a variety of applications.
[0055] like Figure 3 As shown, in the FTIR spectrum, at 1450 cm⁻¹ -1 The peak observed at 802 cm⁻¹ is due to the symmetrical (OCO) vibrational absorption peak in CMIL-101, confirming the presence of the BDC (phthalic acid) linker in CMIL-101(Cr). After superhydrophobic modification, CMIL-101 / CS in the structure exhibits a peak at 802 cm⁻¹. -1 1091cm -1 and 1260cm -1 The broad peaks represent the tensile vibrations of Si-C, Si-O-Si, and Si-CH3, indicating that PDMS was successfully deposited on the sample.
[0056] Example 2: Application of magnetically responsive multifunctional superhydrophobic biomass aerogel PDMS@CMIL-101 / CS in the removal of microplastic organic matter.
[0057] Method: Add the aerogel to 10 mL of 10 mg·L⁻¹ -1 Microplastics (MPs) were subjected to adsorption by shaking in a solution (pH 7), and residual MPs in the suspension were detected by a fluorescence spectrophotometer.
[0058] The adsorption rate (η) is calculated using the following formula:
[0059]
[0060] In the formula, C0 (mg / L) is the initial concentration of MPs; C t (mg / L) represents the concentration of MPs in the solution after adsorption.
[0061] (I) The effect of adding hydrophobic materials on microplastic removal
[0062] To investigate whether the addition of materials enhanced the performance of aerogels, the adsorption properties of microplastics on aerogels at various stages were studied.
[0063] Pure CS and the two aerogels CMIL-101 / CS and PDMS@CMIL-101 / CS prepared in Example 1 were added to 10 mL of 10 mg·L⁻¹ aerogel. -1 In a microplastic solution (pH 7), adsorption was performed by shaking at 25°C for 1 hour. After adsorption, the material was separated from the sample solution using a magnet under an external magnetic field. The residual MPs in the sample solution were then detected using a fluorescence spectrophotometer. Results are as follows: Figure 4 .
[0064] from Figure 4 As can be seen, the removal rate of MPs increased significantly with the addition of CMIL-101, which is due to the electrostatic attraction and π-π interaction between MPs and CMIL-101. When PDMS was added, the removal rate increased slightly, and the mechanical properties improved. Therefore, PDMS and CMIL-101 significantly enhanced the adsorption performance of the aerogel for microplastics.
[0065] (II) Stability Test
[0066] To explore the mechanical durability and chemical stability of superhydrophobic materials, especially their reusability and operational adaptability.
[0067] Implementation method: Extreme conditions were simulated by cyclic compression of light oil and heavy oil and mechanical friction. The physical and chemical stability of the PDMS@CMIL-101 / CS aerogel were evaluated by placing it in the above environments.
[0068] The results are as follows Figure 5 As shown, Figure 5 (a) shows the mechanical stability measured by sandpaper friction. It can be seen that the superhydrophobic contact angle is still relatively high after multiple cycles. Figure 5 (b) represents the stability of the light oil separation cycle. Figure 5 (c) shows the stability of the heavy oil separation cycle. It can be seen that the separation efficiency remains at a high level after multiple cycles. Therefore, it can be concluded that this PDMS@CMIL-101 / CS aerogel exhibits excellent mechanical durability and chemical stability.
[0069] Example 3: Application of magnetically responsive multifunctional superhydrophobic biomass aerogel PDMS@CMIL-101 / CS in oil-water separation
[0070] The application of aerogel as an adsorbent material in oil-water separation was investigated.
[0071] Adsorption capacity is a standard for evaluating the performance of oil-absorbing materials and can be measured using the following procedure: Weigh a single aerogel, then place it in different types of oils and organic solvents for adsorption tests. After adsorption saturation, remove the aerogel, wipe off the surface oil and organic solvent with filter paper, and then weigh the oil-absorbing aerogel. The adsorption capacity (Q) is calculated using the following formula:
[0072]
[0073] Where m0 and m1 are the weights of the aerogel before and after adsorption, respectively.
[0074] (a) Wetting ability of PDMS@CMIL-101 / CS
[0075] like Figure 6 As shown, water droplets maintain a stable spherical shape on the PDMS@CMIL-101 / CS surface. Figure 6 (a). PDMS@CMIL-101 / CS also exhibits strong repulsion against impacting water flows. Figure 6 (b) Numerous bubbles appeared around the surface of PDMS@CMIL-101 / CS in water, producing a specular reflection phenomenon. Figure 6 (c)
[0076] (II) Saturated adsorption of different oils and organic solvents by PDMS@CMIL-101 / CS
[0077] The saturated adsorption capacity of PDMS@CMIL-101 / CS for three types of oil (engine oil, peanut oil, olive oil) or organic solvents (ethanol, n-hexane, n-pentane, N,N-dimethylformamide, dichloromethane, chloroform, ethyl acetate) was investigated.
[0078] Magnetic responsive superhydrophobic chitosan aerogel PDMS@CMIL-101 / CS was added to an oil-water mixture and allowed to adsorb statically.
[0079] Depend on Figure 7 It is evident that the adsorption capacity depends on the density and viscosity of the oil and organic solvent. The adsorption capacity is lowest when the organic solvent is n-hexane. The adsorption capacity is highest when the oil is peanut oil, reaching 10 times its own weight. The recyclability of these oils and organic solvents was evaluated; after 12 cycles of adsorption and desorption, the adsorption capacity did not decrease significantly. This excellent recyclability is mainly due to the chemical durability, porous structure, and high layer roughness of the PDMS layer.
[0080] (III) Practical Application
[0081] The practical application of PDMS@CMIL-101 / CS oil spill cleanup was investigated, simulating the separation of mixed oil from a mixture under natural conditions. Selective adsorption experiments were conducted using Sudan III-stained n-hexane (light oil) and dichloromethane (heavy oil) mixed with water.
[0082] Depend on Figure 8 It is evident that PDMS@CMIL-101 / CS can selectively adsorb n-hexane and dichloromethane. (From...) Figure 8 As shown in Figure b, when the material comes into contact with n-hexane in the upper layer of water, the n-hexane can be rapidly absorbed into the material within seconds, achieving static separation of n-hexane and water. No red contaminants were observed in the water. Figure 8 As shown in Figure a, when the material comes into contact with dichloromethane in the underwater layer, the dichloromethane can be rapidly absorbed into the material within seconds, achieving static separation of water and dichloromethane. No red contaminants were observed in the water. In summary, this demonstrates that the substance has high separation efficiency and produces no pollution.
[0083] (iv) Continuous oil-water separation capability of PDMS@CMIL-101 / CS
[0084] The continuous oil-water separation capability of PDMS@CMIL-101 / CS was investigated, and the results are as follows: Figure 9 .
[0085] Figure 9 In this process, one end of the peristaltic pump conduit is inserted into PDMS@CMIL-101 / CS, and this end is placed in a light oil / water (heavy oil / water) mixture. Driven by the peristaltic pump, the organic phase is gradually and completely transferred to a beaker at the other end of the conduit. After separation, there is no residue left between the aqueous and organic phases.
[0086] (V) Magnetic response characteristics of PDMS@CMIL-101 / CS
[0087] The magnetic response characteristics of PDMS@CMIL-101 / CS were investigated. Due to the magnetic properties of CMIL-101, PDMS@CMIL-101 / CS floating on the water surface can be easily controlled and moved to a designated contaminated area under the influence of an external magnetic field, thus achieving self-driven oil absorption. This is based on the aforementioned driving principle and structural design.
[0088] Figure 10 Optical images of PDMS@CMIL-101 / CS aerogel in clockwise spiral motion are shown. Under the action of a magnet, PDMS@CMIL-101 / CS accurately and quickly absorbs oil on the water surface according to the spiral trajectory, which also shows that PDMS@CMIL-101 / CS does indeed have the characteristics of magnetic stimulation response.
[0089] (vi) Photothermal conversion performance of PDMS@CMIL-101 / CS
[0090] The photothermal conversion performance of PDMS@CMIL-101 / CS was investigated.
[0091] Figure 11 The permeation behavior of high-viscosity oil (peanut oil) on PDMS@CMIL-101 / CS surfaces was shown with and without simulated sunlight. Without simulated sunlight, it took approximately 7 seconds for the oil droplets to be completely absorbed. Figure 11 (a) In contrast, under one simulated solar radiation, it only takes 2 seconds to completely absorb the same oil droplet. Figure 11 (b) This increased the permeability by nearly three times. Furthermore, the peanut oil exhibited a low-temperature response when exposed to light, indicating that the peanut oil was heated in situ via solar energy harvesting using PDMS@CMIL-101 / CS. This further validates that PDMS@CMIL-101 / CS possesses excellent oleophilic and self-heating properties, which can improve the flow rate of high-viscosity oils and accelerate oil absorption.
[0092] (vii) Investigation of the mechanical stability of magnetically responsive superhydrophobic PDMS@CMIL-101 / CS
[0093] The chemical stability of PDMS@CMIL-101 / CS was investigated. The surface stability and durability of PDMS@CMIL-101 / CS play a crucial role in practical applications.
[0094] like Figure 12 As shown, PDMS@CMIL-101 / CS does not lose its superhydrophobicity and maintains good water resistance when exposed to various harsh environments such as strong salt, strong acid, high temperature and freezing, and the contact angle can still be maintained above 150°, which proves that they have good chemical stability.
Claims
1. A method for preparing a magnetically responsive multifunctional superhydrophobic biomass aerogel, characterized in that, Includes the following steps: 1) Ferric chloride hexahydrate was dissolved in N,N-dimethylformamide to form solution A, and terephthalic acid was dissolved in solution A to form solution B. The molar ratio of ferric chloride hexahydrate to terephthalic acid was 2:
1. The mixture was subjected to hydrothermal reaction at 110°C for 20 hours. After centrifugation, washing, drying, and calcination, CMIL-101 was obtained. 2) Add CMIL-101 to deionized water, add chitosan CS and acetic acid, stir vigorously to form a high-viscosity chitosan hydrogel, freeze dry to obtain CMIL-101 / CS aerogel. 3) Dissolve the hydrophobic material and curing agent in an organic solvent and stir to obtain a uniform suspension. Immerse the CMIL-101 / CS aerogel in the suspension and then vacuum dry the mixture to obtain magnetically responsive multifunctional superhydrophobic chitosan aerogel PDMS@CMIL-101 / CS.
2. The preparation method according to claim 1, characterized in that, In step 1), the calcination condition is calcination at 500°C for 2 hours.
3. The preparation method according to claim 1, characterized in that, In step 2), the chitosan CS:CMIL-101 ratio is 5 to 10:1 by mass.
4. The preparation method according to claim 1, characterized in that, In step 3), the hydrophobic material is selected from stearic acid, lauric acid, PFTEOS or polydimethylsiloxane; the curing agent is diphenylcarbamate; and the organic solvent is n-hexane.
5. The application of the magnetically responsive multifunctional superhydrophobic biomass aerogel PDMS@CMIL-101 / CS prepared by the preparation method according to any one of claims 1-4 as an adsorbent for the removal of organic pollutants.
6. The application according to claim 5, characterized in that, The method is as follows: Take an aqueous solution containing organic pollutants, adjust the solution to neutral, then add magnetically responsive multifunctional superhydrophobic biomass aerogel PDMS@CMIL-101 / CS, shake to adsorb, and then separate using a magnet.
7. The application according to claim 5, characterized in that, The organic pollutant is microplastic organic matter.
8. The application of the magnetically responsive multifunctional superhydrophobic biomass aerogel PDMS@CMIL-101 / CS prepared by the preparation method according to any one of claims 1-4 as an adsorbent in oil-water separation.
9. The application according to claim 8, characterized in that, The method is as follows: Add magnetically responsive superhydrophobic chitosan aerogel PDMS@CMIL-101 / CS to the oil-water mixture and allow it to stand for adsorption.
10. The application according to claim 9, characterized in that, The oils include n-hexane, n-pentane, dichloromethane, ethyl acetate, N,N-dimethylformamide, chloroform, engine oil, peanut oil, or olive oil.