A waste corrugated paper / bentonite aerogel as well as a preparation method and application thereof

Abstract

The application discloses a kind of waste corrugated paper / bentonite aerogel and its preparation method and application, belong to oil-water separation material technical field.The application first utilizes the whole component waste corrugated paper including lignin, cellulose and hemicellulose etc.and bentonite to carry out synergic modification to CMC, WSC base aerogel, by limiting the adding order of raw material and preparation step, by the unique electrostatic-hydrogen bond-physical interpenetration synergic effect of bentonite and corrugated paper fiber, make each raw material reaction obtain stable three-dimensional network structure aerogel, then carry out hydrophobic modification, obtain waste corrugated paper / bentonite aerogel.Benefiting from organic-inorganic synergic effect, waste corrugated paper / bentonite aerogel prepared by the application has the characteristics of high porosity, light weight, high mechanical strength, good forming ability, excellent hydrophobic oleophilic performance and high reusability.As oil-water separation material, different oil products can be efficiently adsorbed and rapidly separated.

Description

Technical Field

[0001] This invention belongs to the field of oil-water separation materials technology, specifically relating to a waste corrugated paper / bentonite aerogel, its preparation method, and its application. Background Technology

[0002] Currently, biomass aerogels have received widespread attention in the field of oil-water separation due to their low cost, ease of modification, reusability, and environmental friendliness. However, single biomass aerogels generally suffer from the following problems: (1) insufficient oil-water separation efficiency, making it difficult to quickly and effectively separate oil-water mixtures; (2) low mechanical strength, making them prone to damage during adsorption and extrusion, affecting their service life. How to effectively introduce inorganic fillers (such as bentonite) and form a strong synergistic cross-linking structure with organic fiber networks remains a key challenge to improve the mechanical properties of aerogels; (3) poor reusability, with adsorption performance significantly decreasing after multiple adsorption-desorption cycles, which limits their practical application; (4) in existing technologies, when modifying aerogels with cellulose materials, it is often necessary to perform complex chemical treatments on the raw materials (such as waste paper) to extract pure cellulose components. The process is complex and fails to fully utilize its natural components. Summary of the Invention

[0003] The purpose of this invention is to provide a waste corrugated paper / bentonite aerogel, its preparation method, and its application. Through the synergistic modification of waste corrugated paper and bentonite, a composite aerogel is prepared, solving the problems of low adsorption efficiency, low mechanical strength, and poor reusability of existing biomass aerogels. Furthermore, it achieves high-value utilization of waste resources, promotes the development of oil-water separation technology, and has significant implications for environmental protection and the economy.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] One of the technical solutions of this invention is to provide a method for preparing waste corrugated paper / bentonite aerogel, comprising the following steps:

[0006] Water-soluble chitosan (WSC), pulverized waste corrugated paper (WCP), and bentonite (BT) are added sequentially to a preheated aqueous solution of sodium carboxymethyl cellulose (CMC). After the reaction is kept at a constant temperature and then cooled, the mixture is freeze-dried to obtain an intermediate aerogel. The intermediate aerogel is then hydrophobically modified to obtain the waste corrugated paper / bentonite aerogel.

[0007] The pulverized waste corrugated paper used in this invention contains all components of lignin, cellulose, and hemicellulose, and when used to prepare aerogels, there is no need for complex pure cellulose extraction.

[0008] The layered structure of the bentonite used in this invention and its negative surface charge can generate electrostatic attraction and form interactive hydrogen bonds with the hydroxyl groups (mainly from cellulose and hemicellulose) and phenolic hydroxyl groups (from lignin) in the waste corrugated paper fibers used in the invention. At the same time, WCP fibers play a physical reinforcing and bridging role in the three-dimensional network, together forming a stable three-dimensional network structure.

[0009] Preferably, the mass ratio of sodium carboxymethyl cellulose in the sodium carboxymethyl cellulose aqueous solution to water-soluble chitosan, pulverized waste corrugated paper and bentonite is 3-5:0.8-1.2:0.8-1.2:0.4.

[0010] Preferably, the sodium carboxymethyl cellulose aqueous solution contains 1% sodium carboxymethyl cellulose by mass.

[0011] Preferably, the preheating temperature is 65°C.

[0012] Preferably, the temperature of the heat preservation reaction is 65°C and the time is 4 to 6 hours.

[0013] Preferably, the pulverized waste corrugated paper is in the form of flocculent material; and the bentonite has a particle size of <25μm.

[0014] Preferably, the freeze-drying temperature is -50 to -70°C and the time is 36 to 72 hours.

[0015] Preferably, the specific steps of the hydrophobic modification include: immersing the intermediate aerogel in an octadecyltrichlorosilane (OTS) solution to complete the hydrophobic modification.

[0016] More preferably, the concentration of the octadecyltrichlorosilane (>85.0% (GC)) solution is 1 wt.%, and the immersion time is 30 min.

[0017] The second technical solution of the present invention is to provide a waste corrugated paper / bentonite aerogel prepared according to the above-mentioned preparation method of waste corrugated paper / bentonite aerogel.

[0018] The third technical solution of the present invention provides an application of the above-mentioned waste corrugated paper / bentonite aerogel in oil-water separation.

[0019] The beneficial technical effects of the present invention are as follows:

[0020] This invention first utilizes waste corrugated paper containing lignin, cellulose, and hemicellulose, along with bentonite, to synergistically modify aerogels based on CMC and WSC substrates. By limiting the order of raw material addition and preparation steps, and leveraging the unique electrostatic-hydrogen bonding-physical interpenetration synergy between bentonite and corrugated paper fibers, a stable three-dimensional network structure of aerogel is obtained through the reaction of each raw material. Then, hydrophobic modification is performed to obtain a waste corrugated paper / bentonite aerogel. Benefiting from the organic-inorganic synergy, the waste corrugated paper / bentonite aerogel prepared by this invention exhibits high porosity, lightweight, high mechanical strength, good molding ability, excellent hydrophobic and oleophilic properties, and high reusability. The preparation method provided by this invention directly utilizes the complete components of waste corrugated paper, eliminating the need for complex chemical component separation steps, simplifying the process and reducing costs. As an oil-water separation material, it can achieve efficient adsorption of different oils and rapid oil-water separation. Attached Figure Description

[0021] Figure 1 The XRD patterns of CMC / WSC / WCP / BT prepared in Example 1 and the raw materials BT, WCP, WSC and CMC used are shown.

[0022] Figure 2 Infrared spectra of CMC / WSC / WCP / BT prepared in Example 1, the original CMC / WSC / WCP / BT prepared in Comparative Example 5, and the raw materials BT, WCP, WSC and CMC.

[0023] Figure 3 SEM image (a), energy spectrum (b), and elemental distribution (c) of CMC / WSC / WCP / BT prepared in Example 1.

[0024] Figure 4 The N2 adsorption-desorption isotherm and pore size distribution curves of the aerogels prepared in Example 1 and Comparative Example 1 are shown in (a), the N2 adsorption-desorption isotherm and pore size distribution curves of the aerogels prepared in Comparative Examples 2 to 4 are shown in (b), and the mercury porosimetry analysis curve of the aerogel prepared in Example 1 is shown in (c).

[0025] Figure 5 The diagram shows the adsorption-desorption of cyclohexane by aerogel (a) and the change in adsorption amount during 10 adsorption-desorption cycles of cyclohexane by CMC / WSC / WCP / BT prepared in Example 1 (b).

[0026] Figure 6 A schematic diagram (a) of the compression resilience test of the CMC / WSC / WCP / BT prepared in Example 1, and stress-strain curves (b) of the aerogels prepared in Example 1, Comparative Example 2, and Comparative Example 3 at 60% maximum strain. Detailed Implementation

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0028] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0029] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0031] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0032] Unless otherwise specified, room temperature or normal temperature in this invention refers to a temperature of 20±10℃.

[0033] The preparation steps of the corrugated paper fiber used in the embodiments and comparative examples of this invention are as follows: remove the tape and labels on the waste corrugated cardboard box, cut the corrugated paper into pieces of about 1cm×1cm, put them into a solid sample crusher (Xinhang Instrument Factory, Jintan City, XA-2), crush them at a speed of 25000r / min for 10min, and obtain corrugated paper fiber containing lignin, cellulose and hemicellulose.

[0034] Example 1

[0035] Preparation of waste corrugated paper / bentonite aerogel:

[0036] Add 1.0g of CMC powder to 99mL of ultrapure water and mechanically stir at 400rpm for 4h to completely dissolve it, obtaining a 1% CMC precursor solution. Store the solution in a refrigerator at -4℃ for later use.

[0037] Take 40g of the obtained CMC precursor solution and mechanically stir it in a water bath at 65℃ for 0.5h. Then add 0.1g of WSC, 0.1g of WCP and 0.04g of BT in sequence. Continue the reaction at 65℃ for 4h, then cool to room temperature, freeze to solid at -15℃, and freeze-dry at -70℃ for 36h to obtain intermediate aerogel. Immerse the obtained intermediate aerogel in 1wt.% OTS (>85.0% (GC)) solution for 30 minutes for hydrophobic modification. After drying, waste corrugated paper / bentonite aerogel is obtained, denoted as CMC / WSC / WCP / BT.

[0038] Performance data:

[0039] Adsorption capacity: The adsorption capacity of waste engine oil is reduced to 47.00 g / g; Mechanical strength: The compressive stress at 60% strain is 16.25 kPa; Porosity: 91.08%; Cyclic performance: The adsorption capacity remains at 30% after 10 cycles.

[0040] Example 2

[0041] Low CMC dosage aerogel (0.3g):

[0042] Raw material ratio:

[0043] CMC 0.3g, WSC 0.1g, WCP 0.1g, BT 0.04g.

[0044] Preparation method:

[0045] Same as Example 1.

[0046] Performance data:

[0047] Adsorption capacity: The adsorption capacity of waste engine oil decreased to 35.52 g / g; Mechanical strength: The compressive stress at 60% strain was 12.38 kPa (24% lower than in Example 1); Porosity: 86.5% (compared to 91.08% in Example 1); Analysis: Insufficient CMC led to a decrease in crosslinking density, incomplete pore structure, and decreased adsorption performance.

[0048] Example 3

[0049] High CMC dosage aerogel (0.5g):

[0050] Raw material ratio:

[0051] CMC 0.5g, WSC 0.1g, WCP 0.1g, BT 0.04g.

[0052] Preparation method:

[0053] Same as Example 1.

[0054] Performance data:

[0055] Adsorption capacity: The adsorption capacity of waste engine oil is 41.03 g / g; Mechanical strength: The compressive stress at 60% strain is 14.72 kPa (9.4% lower than in Example 1); Porosity: 89.2% (pore size distribution is biased towards small pores, and large pores are reduced); Analysis: Excessive CMC leads to an increase in solution viscosity, and pore collapse occurs during freeze-drying, limiting adsorption capacity.

[0056] Example 4

[0057] Combined adjustment of WSC and WCP dosage:

[0058] Raw material ratio:

[0059] CMC 0.4g, WSC 0.08g, WCP 0.12g, BT 0.04g.

[0060] Preparation method:

[0061] Same as Example 1.

[0062] Performance data:

[0063] Adsorption capacity: The adsorption capacity of waste engine oil was 43.15 g / g; SEM analysis: The WCP fibers were unevenly distributed, and clusters appeared in some areas; Cycling performance: After 10 cycles, the adsorption capacity remained at 25% (compared to 30% in Example 1); Analysis: The reduction of WSC weakened the amino cross-linking effect, and the excessive WCP led to fiber accumulation, affecting the structural stability.

[0064] The performance of the aerogels prepared in Examples 1-4 and Comparative Example 1 was tested, and the data are shown in Table 1:

[0065] Table 1

[0066]

[0067] Table 1 shows that the optimal porosity and adsorption capacity of the aerogel were achieved when the CMC dosage was 0.4 g (91.08%, 47.00 g / g). Synergistic modification: The addition of WCP and BT significantly improved mechanical strength (+59%) and hydrophobicity (contact angle +26°). Recyclability: Example 1 maintained 30% adsorption capacity after 10 cycles.

[0068] Comparative Example 1

[0069] Preparation of CMC Aerogel

[0070] Add 1.0g of CMC powder to 99mL of ultrapure water and mechanically stir at 400rpm for 4h to completely dissolve it, obtaining a 1% CMC precursor solution. Store the solution in a refrigerator at -4℃ for later use.

[0071] Take 40g of the obtained CMC precursor solution, mechanically stir it in a water bath at 65℃ for 4.5h, then cool it to room temperature, freeze it to solid at -15℃, and then freeze-dry it at -70℃ for 36h to obtain an intermediate aerogel; immerse the obtained intermediate aerogel in a 1wt.% OTS (>85.0% (GC)) solution for 30 minutes for hydrophobic modification, remove it and dry it to obtain CMC aerogel, denoted as CMC.

[0072] Comparative Example 2

[0073] Preparation of CMC / WSC aerogel:

[0074] Add 1.0g of CMC powder to 99mL of ultrapure water and mechanically stir at 400rpm for 4h to completely dissolve it, obtaining a 1% CMC precursor solution. Store the solution in a refrigerator at -4℃ for later use.

[0075] Take 40g of the obtained CMC precursor solution and mechanically stir it in a water bath at 65℃ for 0.5h. Add 0.1g of WSC and continue the reaction at 65℃ for 4h. Then cool to room temperature, freeze it into a solid at -15℃, and freeze-dry it at -70℃ for 36h to obtain an intermediate aerogel. Immerse the obtained intermediate aerogel in a 1wt.% OTS (>85.0% (GC)) solution for 30 minutes for hydrophobic modification. After drying, obtain CMC / WSC aerogel, denoted as CMC / WSC.

[0076] Comparative Example 3

[0077] Preparation of CMC / WSC / BT aerogels:

[0078] Add 1.0g of CMC powder to 99mL of ultrapure water and mechanically stir at 400rpm for 4h to completely dissolve it, obtaining a 1% CMC precursor solution. Store the solution in a refrigerator at -4℃ for later use.

[0079] Take 40g of the obtained CMC precursor solution and mechanically stir it in a water bath at 65℃ for 0.5h. Then add 0.1g of WSC and 0.04g of BT sequentially, continue the reaction at 65℃ for 4h, cool to room temperature, freeze to solid at -15℃, and freeze-dry at -70℃ for 36h to obtain an intermediate aerogel. Immerse the obtained intermediate aerogel in a 1wt.% OTS (>85.0% (GC)) solution for 30 minutes for hydrophobic modification, remove and dry to obtain CMC / WSC / BT aerogel, denoted as CMC / WSC / BT.

[0080] Comparative Example 4

[0081] Preparation of CMC / WSC / WCP aerogels:

[0082] Add 1.0g of CMC powder to 99mL of ultrapure water and mechanically stir at 400rpm for 4h to completely dissolve it, obtaining a 1% CMC precursor solution. Store the solution in a refrigerator at -4℃ for later use.

[0083] Take 40g of the obtained CMC precursor solution and mechanically stir it in a water bath at 65℃ for 0.5h. Then add 0.1g of WSC and 0.1g of WCP sequentially, continue the reaction at 65℃ for 4h, cool to room temperature, freeze to solid at -15℃, and freeze-dry at -70℃ for 36h to obtain intermediate aerogel. Immerse the obtained intermediate aerogel in 1wt.% OTS (>85.0% (GC)) solution for 30 minutes for hydrophobic modification, remove and dry to obtain CMC / WSC / WCP aerogel, denoted as CMC / WSC / WCP.

[0084] Comparative Example 5

[0085] Preparation of raw waste corrugated paper / bentonite aerogel:

[0086] Add 1.0g of CMC powder to 99mL of ultrapure water and mechanically stir at 400rpm for 4h to completely dissolve it, obtaining a 1% CMC precursor solution. Store the solution in a refrigerator at -4℃ for later use.

[0087] Take 40g of the obtained CMC precursor solution and mechanically stir it in a water bath at 65℃ for 0.5h. Then add 0.1g of WSC, 0.1g of WCP and 0.04g of BT in sequence. Continue to react at 65℃ for 4h. Then cool to room temperature, freeze to solid at -15℃, and freeze dry at -70℃ for 36h to obtain the original waste corrugated paper / bentonite aerogel, denoted as original CMC / WSC / WCP / BT.

[0088] The XRD patterns of the CMC / WSC / WCP / BT prepared in Example 1 and the raw materials BT, WCP, WSC and CMC used are shown in the figure. Figure 1 .

[0089] from Figure 1As can be seen from the spectra, the CMC and WSC spectra exhibit broad diffraction peaks at 2θ = 19.92° and 2θ = 18.64°, respectively, confirming their amorphous structures. The WCP spectra show two broad diffraction peaks in the range of 14°–24°, mainly attributed to the amorphous structures of hemicellulose and lignin. The characteristic diffraction peaks at 15.98° and 22.5° correspond to the (101) and (002) crystal planes of cellulose type I, while the diffraction peak at 29.5° may be due to untreated impurities. The BT spectra show diffraction peaks at 6.94°, 19.8°, 21.83°, 26.62°, 29.38°, 36.02°, and 61.98°, which are typical diffraction peaks of montmorillonite and quartz. The diffraction pattern of the CMC / WSC / WCP / BT aerogel only shows a broad diffraction peak around 21°, which may be due to the relatively small amounts of WCP and BT added. However, compared to the main component CMC, the diffraction peak of the CMC / WSC / WCP / BT aerogel is significantly shifted to the right, indicating that the addition of WCP and BT caused a change in the morphology of CMC, providing preliminary evidence that the CMC / WSC / WCP / BT aerogel may have been successfully composited.

[0090] The infrared spectra of the CMC / WSC / WCP / BT prepared in Example 1, the original CMC / WSC / WCP / BT prepared in Comparative Example 5, and the raw materials BT, WCP, WSC, and CMC are shown below. Figure 2 .

[0091] from Figure 2 As can be seen from the data, CMC, WSC, WCP, BT, the original CMC / WSC / WCP / BT and CMC / WSC / WCP / BT aerogels exhibit properties at depths of 550–4000 cm⁻¹. -1 Within the wavenumber range, all materials are at 3465 cm⁻¹ -1 Broad peaks are observed in the vicinity, which can be attributed to the stretching vibration of the OH group. In CMC, due to the asymmetric stretching and symmetric vibration of the carboxylate ion, two peaks appear at 1600 cm⁻¹. -1 and 1415cm -1 The characteristic peak of BT is at 3626 cm⁻¹. -1 and 1640cm -1 The peak values ​​at 1044 cm⁻¹ reflect the OH stretching vibrations of water molecules on the surface and between the interlayers, respectively. -1 and 791cm -1 The main characteristic peaks at these locations represent the Si-O bending vibration peak and the Si-O-Si asymmetric stretching vibration peak, respectively. In the WCP spectrum, the peaks are located at 3500–3300 cm⁻¹. -1 The broad peaks at the wavenumbers correspond to the stretching vibrations of OH groups in cellulose and hemicellulose, at 2920 cm⁻¹ and 1644 cm⁻¹. -1 and 1045cm-1 The nearby peaks correspond to stretching vibrations of CH, C=C in the aromatic ring skeleton, and C=O in cellulose, respectively. The WSC spectrum shows peaks in the 3500–3300 cm⁻¹ range. -1 The adsorption band is attributed to the stretching vibrations of the OH and NH groups in the polysaccharide structure, 2920 cm⁻¹. -1 and 2873cm -1 The peak values ​​at 1645 cm⁻¹ are attributed to the stretching vibrations of the -CH₃ and -CH₂ groups, respectively. -1 The nearby peaks are C=O stretching vibration peaks of acetylated groups. Compared to the unit materials, in the original CMC / WSC / WCP / BT and CMC / WSC / WCP / BT aerogels, the peak at 2920 cm⁻¹ is significantly higher. -1 1640cm -1 and 1415cm -1 The peak intensities in the vicinity of the aerogel are significantly reduced, indicating enhanced intermolecular hydrogen bonding. This is likely due to the formation of hydrogen bonds between the hydroxyl groups in WCP and BT, and between the hydroxyl and amino groups in WSC and the hydroxyl and carboxyl groups in CMC, thus enhancing the intermolecular interactions within the CMC / WSC / WCP / BT aerogel and constructing a stable three-dimensional network structure. Furthermore, compared to the original CMC / WSC / WCP / BT aerogel, the CMC / WSC / WCP / BT aerogel exhibits a significantly reduced peak intensity at 2920 cm⁻¹. -1 The stretching vibration peak representing -CH3 is significantly enhanced, which may be because the OTS in the hydrophobic agent undergoes dehydration condensation with the hydroxyl groups in the aerogel, increasing the number of CH, proving that OTS is grafted onto the aerogel surface.

[0092] The SEM images (a), energy dispersive spectroscopy (b), and elemental distribution map (c) of the CMC / WSC / WCP / BT prepared in Example 1 are shown below. Figure 3 .

[0093] from Figure 3 As can be seen, C, O, Na, Si, Al, and N elements are all present in this composite aerogel. The figures show that Si and Al elements, derived from BT, are mainly distributed in the rough areas of the lamellar structure, a result corroborated by the analysis of the scanning electron microscopy images. Meanwhile, C, O, and Na elements, mainly derived from CMC, WSC, and WCP, are the most abundant host elements, uniformly distributed on the surface of the original CMC / WSC / WCP / BT aerogel. Notably, compared to the gel surface, the elements are significantly less abundant in the pores, effectively demonstrating the 3D structure of the original CMC / WSC / WCP / BT aerogel. Furthermore, only a small amount of N element was detected in the original CMC / WSC / WCP / BT aerogel, which also indirectly confirms that the amount of WSC added to the composite aerogel is low, but it is indeed present in the composite aerogel.

[0094] The N2 adsorption-desorption isotherms and pore size distribution curves of the aerogels prepared in Examples 1 and 1 (a), the N2 adsorption-desorption isotherms and pore size distribution curves of the aerogels prepared in Examples 2-4 (b), and the mercury porosimetry analysis curve of the aerogel prepared in Example 1 (c) are shown in the figures. Figure 4 .

[0095] from Figure 4 As can be seen, the N2 adsorption-desorption isotherms of all aerogels conform to Type IV curves. In the low-to-medium pressure region of P / P0, all aerogels exhibit relatively slow adsorption rates. When P / P0 > 0.85, the isotherms of all aerogels rise sharply. After the sharp rise in isotherms, the adsorption and desorption curves of all aerogels form a hysteresis loop, which is particularly evident in CMC / WSC / WCP / BT, indicating their porous structure. Furthermore, from... Figure 4 The pore size distribution diagrams in (a) and (b) also show that the pore sizes of all aerogels are mainly distributed in the range of 0–50 nm, belonging to the mesoporous category. Larger pores, with a maximum diameter of approximately 220 nm, were also observed in the CMC / WSC / WCP / BT aerogels, further demonstrating their porous structure, with mesopores and macropores being the main pore types. The macroporous structure of the CMC / WSC / WCP / BT aerogels was tested using a fully automated mercury porosimeter (MIP). Figure 4 The porosity of the CMC / WSC / WCP / BT is 91.08%. The pore size is mainly distributed between 50 and 175 μm, with the highest peak at 100 μm, indicating that it contains abundant macropores. This further shows that the pore size structure of CMC / WSC / WCP / BT is effectively increased due to the addition of BT and WCP, which is very beneficial to the adsorption of oil. Therefore, it has a large adsorption capacity and efficient oil-water separation performance.

[0096] Using cyclohexane as the target, the oil adsorption capacity of CMC / WSC / WCP / BT prepared in Example 1 was tested, and then 10 adsorption-desorption cycles were performed to examine the reusability of each aerogel.

[0097] like Figure 5 As shown in Figure (a), adsorbed cyclohexane can be easily desorbed from CMC / WSC / WCP / BT aerogel through simple manual extrusion. The extruded CMC / WSC / WCP / BT aerogel can essentially recover its original shape after the external force is removed, preliminarily demonstrating its good reusability. To further investigate the recycling performance of CMC / WSC / WCP / BT aerogel, 10 adsorption-desorption cycle experiments were conducted using the extrusion method. The results are shown in Figure (a). Figure 5As shown in Figure (b), after the first extrusion, the aerogel's adsorption capacity for cyclohexane decreased to 60% of the original adsorption capacity. In the subsequent five extrusions, it remained relatively stable at around 50% of the original adsorption capacity, eventually gradually decreasing to 30%. This decrease in adsorption capacity may be due to the partial shrinkage and collapse of the aerogel's porous structure. However, overall, the CMC / WSC / WCP / BT aerogel exhibits good recyclability, and the absorbed oil can be recovered through simple mechanical extrusion.

[0098] The mechanical strength of the aerogels prepared in Example 1, Comparative Example 2, and Comparative Example 3 was tested.

[0099] Good mechanical properties are one of the key factors for the stable and recyclable use of adsorbent materials. For example... Figure 6 As shown in Figure (a), the CMC / WSC / WCP / BT aerogel exhibits significant compressive deformation under a 500g weight and rebounds to its original height within 3 seconds after pressure release. This demonstrates that the CMC / WSC / WCP / BT aerogel possesses excellent compressive resilience, providing a good foundation for cyclic extrusion oil absorption / release. Furthermore, the compressive strength of the three aerogels (CMC / WSC, CMC / WSC / BT, and CMC / WSC / WCP / BT) was investigated using stress-strain curves. Figure 6 As shown in (b), at 60% of the maximum strain, the compressive stresses of CMC / WSC, CMC / WSC / BT, and CMC / WSC / WCP / BT aerogels are 10.19 kPa, 13.36 kPa, and 16.25 kPa, respectively, with the compressive stress gradually increasing. This may be because BT and WCP not only enhance the crosslinking density of CMC and WSC, but also form hydrogen bonds with CMC / WSC, promoting the formation of a more stable three-dimensional network structure in the aerogel, thereby enhancing its mechanical properties. This helps it maintain good structural stability under repeated compression and avoids structural collapse.

[0100] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing waste corrugated paper / bentonite aerogel, characterized in that, Includes the following steps: Water-soluble chitosan, pulverized waste corrugated paper, and bentonite were added sequentially to a preheated sodium carboxymethyl cellulose aqueous solution. After the reaction was kept at a constant temperature and cooled, the mixture was freeze-dried to obtain an intermediate aerogel. The intermediate aerogel was then hydrophobically modified to obtain the waste corrugated paper / bentonite aerogel. The mass ratio of sodium carboxymethyl cellulose in the sodium carboxymethyl cellulose aqueous solution to water-soluble chitosan, pulverized waste corrugated paper and bentonite is 3~5:0.8~1.2:0.8~1.2:0.

4.

2. The method for preparing waste corrugated paper / bentonite aerogel according to claim 1, characterized in that, The sodium carboxymethyl cellulose aqueous solution contains 0.75% to 1.25% sodium carboxymethyl cellulose by mass.

3. The method for preparing waste corrugated paper / bentonite aerogel according to claim 1, characterized in that, The preheating temperature is 65°C.

4. The method for preparing waste corrugated paper / bentonite aerogel according to claim 1, characterized in that, The temperature of the heat preservation reaction is 65℃, and the time is 4~6h.

5. The method for preparing waste corrugated paper / bentonite aerogel according to claim 1, characterized in that, The pulverized waste corrugated paper is in a flocculent state; the bentonite has a particle size of <25µm.

6. The method for preparing waste corrugated paper / bentonite aerogel according to claim 1, characterized in that, The freeze-drying temperature is -50~-70℃, and the time is 36~72h.

7. The method for preparing waste corrugated paper / bentonite aerogel according to claim 1, characterized in that, The specific steps of the hydrophobic modification include: immersing the intermediate aerogel in an octadecyltrichlorosilane solution to complete the hydrophobic modification.

8. A waste corrugated paper / bentonite aerogel prepared by the method of preparing waste corrugated paper / bentonite aerogel according to any one of claims 1 to 7.

9. The application of the waste corrugated paper / bentonite aerogel according to claim 8 in oil-water separation.

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