Preparation method and application of directional hole sponge body

Abstract

The invention belongs to the technical field of directional hole sponge body preparation, and particularly discloses a preparation method and application of a directional hole sponge body. The preparation method comprises the following steps: cross-linking aminated silane and carbon nanotubes, and forming directional holes by using a directional heating method; the surface of the sponge is further coated with a photo-thermal conversion functional layer and a hydrophobic layer, and the directional hole hydrophobic sponge with the photo-thermal conversion effect is obtained. The obtained sponge has hydrophobicity and rebound resilience, can selectively adsorb oil in water, has an excellent adsorption rate, can be recycled for multiple times by using a physical compression method, and has a good application prospect in the field of oil-water separation.

Description

Technical Field

[0001] This invention belongs to the field of chemical separation, specifically relating to a method for preparing and applying a directional porous sponge. Background Technology

[0002] Crude oil and its products play a vital role in the global economy. Oil spills are an unavoidable risk during crude oil extraction, production, and transportation. In recent years, the use of adsorbents to treat oily wastewater has become a common method. Utilizing the different wettabilities of oil and water to selectively adsorb dispersed oil onto porous hydrophobic materials is key to oil-water separation. Among these, oil-absorbing sponges, due to their three-dimensional porous structure, possess a high adsorption capacity and have significant advantages in oil-water separation applications.

[0003] Rapid water transport in trees relies on the sieve-like structure arranged in the xylem; the ordered pore structure is a key factor in resisting gravity-driven liquid transport. Similarly, the internal microstructure of porous materials affects their liquid transport rate. Ordered pore structures can reduce resistance to liquid transport, enabling rapid liquid absorption and transport, while disordered porous materials exhibit significant resistance to liquid transport. Existing methods for preparing oriented porous sponges mainly employ oriented cryotemplation, such as CN202310837817.3, which discloses a polysaccharide sponge with an oriented pore structure and its preparation method. Another method utilizes existing natural materials to obtain oriented pores, such as CN201910068918.2, which discloses a method for preparing a mushroom-stem-inspired oriented oil-absorbing material. While both methods can yield regular oriented pore structures, they limit the selection of raw materials, and the synthesized sponges generally have poor mechanical properties. Currently, most sponges with good mechanical properties in the field of oil-water separation are elastomers. For example, CN202110075962.3 discloses a method for preparing a self-foaming graphene oxide-polydimethylsiloxane sponge. The invented sponge has excellent elasticity and can be recycled, but it lacks an ordered pore structure and cannot achieve a high adsorption rate. Summary of the Invention

[0004] To address the aforementioned problems, this invention employs a directional heating method to foam the sponge, obtaining a sponge matrix with a directional pore structure. This sponge matrix can enhance the adsorption rate of oils. Subsequently, 2,2,6,6-tetramethylpiperidine oxide and dopamine are copolymerized on the surface of the sponge matrix, giving the sponge photothermal conversion properties. Finally, a polydimethylsiloxane hydrophobic layer is coated on its surface to increase the sponge's hydrophobicity and stability.

[0005] The method for preparing the oriented porous sponge of the present invention includes the following steps: (1) Dissolve the aminated silane (preferably amino-terminated polydimethylsiloxane) in an organic solvent and stir until homogeneous to obtain an aminated silane solution.

[0006] Furthermore, the organic solvent is an organic solvent with similar solubility parameters to the aminated silane and is easily volatile, and may be one or more of tetrahydrofuran (THF), dichloromethane (DCM), chloroform, and 1,4-dioxane, preferably tetrahydrofuran.

[0007] (2) Add carboxylated multi-walled carbon nanotube dispersion to the aminated silane solution in step (1), stir evenly, and obtain a mixed solution.

[0008] Furthermore, the concentration of the carboxylated multi-walled carbon nanotube dispersion is 10 mg / mL; the mass ratio of the aminated silane to the carboxylated multi-walled carbon nanotubes is 1000:3.

[0009] (3) Add the condensing agent and glutaraldehyde to the mixed solution in step (2) and stir evenly at room temperature.

[0010] Further, the condensing agent is selected as a combination of 1-(3-dimethylaminopropyl)-3-ethyl (EDC) and N-hydroxysuccinimide (NHS), wherein the molar ratio of polydimethylsiloxane:EDC:NHS is 1:10:10, and the amount of glutaraldehyde added is 1.0 wt. of the aminated silane.

[0011] (4) Transfer the mixed solution obtained in step (3) into a mold and irradiate the top of the mixed solution with a xenon lamp for 10-20 minutes to obtain a directional porous sponge.

[0012] Furthermore, the irradiation intensity is 1.0-1.5 solar irradiance.

[0013] The oriented porous sponge prepared by the above method is used to prepare a photothermal conversion oil-absorbing sponge. The specific steps are as follows: The oriented porous sponge was immersed in a mixed solution of 2,2,6,6-tetramethylpiperidine oxide and dopamine for 12 hours, then washed with ethanol and air-dried. The above steps were repeated twice to obtain the sponge. Glutaraldehyde was added to a solution of aminated silane with a concentration of 0.1 g / mL. The sponge was then immersed in the solution for 10 minutes and removed to air dry naturally, thus obtaining a directional porous photothermal conversion oil-absorbing sponge.

[0014] Furthermore, the mass ratio of 2,2,6,6-tetramethylpiperidine oxide to dopamine is 1:1.

[0015] Furthermore, the mass ratio of the aminated silane to glutaraldehyde is 50:1.

[0016] The directional pore formation mechanism of the present invention is as follows: an amino-modified silane undergoes a condensation reaction with a carboxylated multi-walled carbon nanotube, and the resulting gaseous byproducts escape under heating conditions to form pores. When a xenon lamp is used to irradiate from the top, the gas tends to escape from the top, thereby forming directional pores from the bottom up.

[0017] Compared with existing technologies, the advantages of the technical solution of this invention are as follows: This invention uses a directional heating method to create directional pores in the sponge during the preparation process, which results in a higher adsorption rate for oils compared to disordered pore structures. Attached Figure Description

[0018] Figure 1 The images shown are SEM images of the pore structure of the directional porous photothermal conversion oil-absorbing sponge prepared in Example 1 of the present invention, wherein Figure a is a cross-section and Figure b is a longitudinal section. Figure 2 The water contact angle of the directional porous photothermal conversion oil-absorbing sponge prepared in Example 1 of the invention; Figure 3 Compression cycle curve of the directional porous photothermal conversion oil-absorbing sponge prepared in Example 1 of the invention; Figure 4 The adsorption capacity and sponge mass change curves of the directional porous photothermal conversion oil-absorbing sponge prepared in Example 1 of the invention for kerosene adsorption-desorption. Figure 5 The curves showing the change in the adsorption capacity of the photothermal conversion oil-absorbing sponge prepared in Examples 1, 2, and 3 of the invention, as well as Comparative Examples 1 and 2, for kerosene under a light intensity of 1 ray of sunlight over time. Figure 6 A cross-sectional image of the photothermal conversion oil-absorbing sponge prepared for Comparative Example 1 of the invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Example 1

[0021] (1) Weigh 1g of amino-terminated polydimethylsiloxane PDMS (purchased from Gelest, model GEL-DMS-A31, molecular weight 25000), add 1mL of tetrahydrofuran, stir evenly to obtain polydimethylsiloxane solution.

[0022] (2) Take 0.3 mL of 10 mg / mL carboxylated multi-walled carbon nanotubes (purchased from Xianfeng Nano, purity 95%, length 0.5-2, micro carboxyl content 2.00 wt%) dispersion and add it to the polydimethylsiloxane solution in step (1), stir evenly to obtain a mixed solution.

[0023] (3) Add 0.115 g of EDC to the mixed solution in step (2), stir evenly, add 0.065 g of NHS, stir evenly, add 0.01 g of glutaraldehyde, stir evenly, transfer to a cylindrical mold (with an inner diameter of 2 cm and a height of 1 cm), irradiate the top of the mixed solution with a xenon lamp for 15 minutes with a light intensity of 1.2 times the sunlight, and obtain a directional porous sponge.

[0024] Applications of oriented sponges: (4) Weigh 0.2 g of dopamine and dissolve it in 20 mL of water, and dissolve 0.2 g of tetramethylpiperidine (2,2,6,6-tetramethylpiperidine oxide) in 20 mL of water. After mixing the two, immerse the oriented porous sponge obtained in Example 1 in the solution for 12 hours, and then take it out and air dry. Repeat this step twice to obtain the sponge.

[0025] (5) Weigh 0.5 g of amino-terminated polydimethylsiloxane, add 5 mL of tetrahydrofuran, stir evenly, immerse the sponge obtained in step (4) into it, then add 0.01 g of glutaraldehyde, stir evenly, and press the sponge continuously to make the coating solution fully impregnate the sponge. After 10 minutes, take out the sponge and let it air dry naturally to obtain the directional pore photothermal conversion oil-absorbing sponge.

[0026] Figure 1 The images show the pore structure of the directional pore photothermal conversion oil-absorbing sponge prepared in Example 1, where (a) is a cross-section and (b) is a longitudinal section, showing that the sponge forms longitudinal directional pores.

[0027] Figure 2 The image shows a water contact angle test photograph of the directional porous photothermal conversion oil-absorbing sponge prepared in Example 1, with a water contact angle of 145.3°.

[0028] Figure 3 The compression cycle curve of the directional porous photothermal conversion oil-absorbing sponge prepared in Example 1 (cyclic compression at 80% strain displacement and a rate of 20 mm / min) shows that the sponge has excellent elasticity and recovery ability.

[0029] The directional porous photothermal conversion oil-absorbing sponge prepared in Example 1 adsorbed kerosene for 10 minutes under one day of sunlight. The kerosene was then manually squeezed out, and residual kerosene was washed away with petroleum ether. After drying, the sponge was re-adsorbed, and this cycle was repeated 10 times. The changes in adsorption capacity and weight were obtained as follows: Figure 4 As can be seen, sponges have excellent recycling performance.

[0030] Example 2

[0031] (1) Same as Example 1.

[0032] (2) Same as Example 1.

[0033] (3) Add 0.115 g of EDC to the mixed solution in step (2), stir evenly, add 0.065 g of NHS, stir evenly, add 0.01 g of glutaraldehyde, stir evenly, transfer to a mold (a cylinder with an inner diameter of 2 cm and a height of 1 cm), and irradiate the top of the mixed solution with a xenon lamp for 15 minutes with a light intensity of 1.0 solar rays.

[0034] Applications of oriented sponges: (4) Same as Example 1.

[0035] (5) Same as Example 1.

[0036] Example 3

[0037] (1) Same as Example 1.

[0038] (2) Same as Example 1.

[0039] (3) Add 0.115 g of EDC to the mixed solution in step (2), stir well, add 0.065 g of NHS, stir well, add 0.01 g of glutaraldehyde, stir well, transfer to a mold, and irradiate the top of the mixed solution with a xenon lamp for 12 minutes with a light intensity of 1.2 times the sunlight.

[0040] Applications of oriented sponges: (4) Same as Example 1.

[0041] (5) Same as Example 1.

[0042] Comparative Example 1

[0043] (1) Same as Example 1.

[0044] (2) Same as Example 1.

[0045] (3) Add 0.115 g of EDC to the mixed solution in step (2), stir evenly, add 0.065 g of NHS, stir evenly, add 0.01 g of glutaraldehyde, stir evenly, transfer to the mold, and transfer the mold to a 50°C oven for heating and curing for 2 hours.

[0046] Applications of oriented sponges: (4) Same as Example 1.

[0047] (5) Same as Example 1.

[0048] Comparative Example 2

[0049] (1) Same as Example 1.

[0050] (2) Same as Example 1.

[0051] (3) Add 0.115 g of EDC to the mixed solution in step (2), stir evenly, add 0.065 g of NHS, stir evenly, add 0.01 g of glutaraldehyde, stir evenly, transfer to a mold, and irradiate the top of the mixed solution with a xenon lamp for 15 minutes with a light intensity of 1.8 times the sunlight.

[0052] Applications of oriented sponges: (4) Same as Example 1.

[0053] (5) Same as Example 1.

[0054] Figure 6 The image shows the longitudinal section of the directional porous photothermal conversion oil-absorbing sponge prepared for Comparative Example 1. It can be seen that the sponge has disordered and unevenly distributed internal pores.

[0055] Adsorption performance tests of sponges prepared in Examples 1-3 and Comparative Examples 1-2: Test method: First, record the original weight of the photothermal conversion oil-absorbing sponge in different embodiments and comparative examples. Then, place them in kerosene and apply sunlight of 1 intensity to the top. Every once in a while, gently remove them with tweezers and weigh them to record the weight until the adsorption is saturated (constant weight). Divide the subsequent weight by the original weight to obtain the adsorption capacity.

[0056] Test results are as follows Figure 5 As shown.

[0057] from Figure 5 It can be seen that Example 1 has the fastest adsorption rate and the highest adsorption capacity; Example 2, which uses a weaker light intensity to prepare a sponge, has the second-highest adsorption capacity; Example 3 has the same light intensity as Example 1 but a shorter light exposure time, and its adsorption capacity is weaker than that of Example 1; Comparative Example 1 has no oriented pore structure, and its adsorption rate is significantly worse than all examples; Comparative Example 2 has the same light exposure time as Example 1 but its light intensity is too high, and its adsorption capacity is weaker than that of Examples 1-3.

[0058] Compared to Example 2, weaker light intensity in Example 1 may result in insufficient heating at the bottom, hindering the effective generation of escaping gas, leading to a reduction in pores and weakening the adsorption capacity. Compared to Example 3, shorter light exposure time in Example 1 results in incomplete pore formation, affecting adsorption capacity. Compared to Comparative Example 2, excessively high light intensity in Example 1 leads to excessively high solution temperature, causing rapid surface solidification and preventing gas from escaping quickly. This results in gas accumulation inside the sponge, forming large pores and affecting the sponge's adsorption performance.

[0059] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a directional porous sponge, characterized in that, Includes the following steps: Aminated silanes are dissolved in an organic solvent, and carboxylated multi-walled carbon nanotube dispersions are added. After stirring evenly, condensing agents and glutaraldehyde are added, and stirring is continued until evenly mixed. The mixture is then transferred to a mold and cured using a directional heating method to obtain a sponge matrix with directional pores. The directional heating method involves irradiating the top of the mixture with a xenon lamp.

2. The method for preparing a directional porous sponge according to claim 1, characterized in that, The aminated silane is an amino-terminated polydimethylsiloxane.

3. The method for preparing a directional porous sponge according to claim 1, characterized in that, The organic solvent is at least one of tetrahydrofuran, dichloromethane, trichloromethane, and 1,4-dioxane.

4. The method for preparing a directional porous sponge according to claim 1, characterized in that, The concentration of the carboxylated carbon nanotube dispersion is 10 mg / mL; the mass ratio of the aminated silane to the carboxylated multi-walled carbon nanotubes is 1000:

3.

5. The method for preparing a directional porous sponge according to claim 1, characterized in that, The condensing agent is 1-(3-dimethylaminopropyl)-3-ethyl and N-hydroxysuccinimide; the molar ratio of the aminated silane, 1-(3-dimethylaminopropyl)-3-ethyl and N-hydroxysuccinimide is 1:10:

10.

6. The method for preparing a directional porous sponge according to claim 1, characterized in that, The amount of glutaraldehyde added is 1.0 wt% of the aminated silane.

7. The method for preparing a directional porous sponge according to claim 1, characterized in that, The irradiation time is 10-20 minutes, and the irradiation intensity is 1.0-1.5 times the solar intensity.

8. An application of a directional porous sponge prepared according to any one of claims 1-7 in photothermal conversion oil absorption, characterized in that, The oriented porous sponge was immersed in a mixed solution of 2,2,6,6-tetramethylpiperidine oxide and dopamine for 12 hours, then removed and dried. This process was repeated twice. Then, it was immersed in an aminated silane solution with glutaraldehyde added. After stirring evenly, it was immersed for 10 minutes, removed and dried to obtain the oriented porous photothermal conversion oil-absorbing sponge.

9. The application according to claim 8, characterized in that, The mass ratio of 2,2,6,6-tetramethylpiperidine oxide to dopamine is 1:1; the concentration of the aminated silane solution is 0.1 g / mL; and the mass ratio of the aminated silane to glutaraldehyde is 50:1.

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