Photo-thermal hydrophobic composite aerogel for crude oil adsorption and preparation method thereof

Abstract

The invention discloses photo-thermal hydrophobic composite aerogel for crude oil adsorption and a preparation method of the photo-thermal hydrophobic composite aerogel. The composite aerogel is obtained by uniformly mixing a polyvinyl alcohol solution, a copper sulphide-loaded bacterial cellulose dispersion liquid and methyltrimethoxysilane sol, reacting and then sequentially carrying out pre-freezing treatment, freeze drying and heat treatment. The photo-thermal hydrophobic composite aerogel provided by the invention has excellent hydrophobicity and elasticity, large adsorption capacity on oily substances and excellent photo-thermal performance, can be used as an adsorbent for crude oil recovery, can be repeatedly utilized, and has practical popularization and application values.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of device for separating or removing oil or oily substances or similar floating substances, and particularly relates to a photo-thermal hydrophobic composite aerogel for crude oil adsorption and a preparation method thereof. BACKGROUND

[0002] In recent years, frequent oil spillage and large amounts of industrial oily wastewater discharge pose a serious threat to marine ecosystems and human health. Therefore, it is particularly important to develop efficient and environmentally friendly oil spill cleanup technologies. Among the various treatment methods that have been widely used, such as physical adsorption, in-situ combustion, gravity separation, centrifugal separation, and biodegradation, physical adsorption is attracting attention due to its low cost, high efficiency, simple operation, and lack of secondary pollution. Based on these advantages, researchers have successfully prepared a variety of hydrophobic and oleophilic porous adsorbents with high adsorption capacity, and have demonstrated their great potential in practical applications. Among various adsorbents, aerogels have become an adsorbent with great application prospects due to their large specific surface area and high porosity.

[0003] From the perspective of sustainable production and cost-effectiveness, polyvinyl alcohol (PVA) has become an extremely attractive material for aerogel preparation due to its excellent biocompatibility and environmental friendliness. However, the currently developed PVA-based aerogels generally rely on multi-step crosslinking reactions and subsequent hydrophobic modification treatments (such as chemical vapor deposition, impregnation or coating methods) to improve their adsorption performance and hydrophobicity. Such methods generally have some limitations, such as the use of toxic aldehyde crosslinking agents, uneven distribution of hydrophobic modification, and complex preparation process. In addition, most PVA-based aerogels have poor elasticity and are mainly suitable for adsorbing low-density organic solvents and oils, and still perform poorly in handling high-viscosity crude oil and other pollutants with poor fluidity.

[0004] Therefore, to achieve more extensive practical applications, it is of great research significance and application value to develop efficient adsorbents based on polyvinyl alcohol with the aid of a simple preparation process that can adsorb high-viscosity crude oil. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a photo-thermal hydrophobic composite aerogel for crude oil adsorption and a preparation method thereof, which addresses the above-mentioned deficiencies in the prior art. The polyvinyl alcohol-based photo-thermal hydrophobic composite aerogel has good photo-thermal performance and hydrophobicity, a large adsorption capacity for crude oil, can efficiently separate oil-water mixtures, is suitable for marine oil spill treatment, and has a simple preparation method and mild reaction conditions, making it suitable for widespread application.

[0006] The first aspect of the present application provides a photo-thermal hydrophobic composite aerogel for crude oil adsorption, which is obtained by mixing and reacting a polyvinyl alcohol solution, a copper sulfide-loaded bacterial cellulose dispersion solution and a methyltrimethoxysilane sol, and then sequentially performing pre-freezing treatment, freeze-drying and heat treatment.

[0007] According to the above scheme, the water contact angle of the photo-thermal hydrophobic composite aerogel is 120-160°.

[0008] The second aspect of the present application provides a preparation method of a photo-thermal hydrophobic composite aerogel for crude oil adsorption, and the specific steps are as follows: 1) Preparation of a polyvinyl alcohol solution: polyvinyl alcohol is added to water at 85-95°C, and stirred and dissolved to obtain a polyvinyl alcohol solution; 2) Preparation of a copper sulfide-loaded bacterial cellulose dispersion solution: an ammonia solution is added to a copper sulfate solution, and a deep blue copper-ammonia complex ion solution is obtained by stirring at room temperature. The obtained copper-ammonia complex ion solution is first added with a bacterial cellulose dispersion solution, and stirred at room temperature (15-40°C) for 1-4 h. Then, a sodium sulfide solution is added, and stirred at room temperature for 2-4 h (the bacterial cellulose contains a large number of hydroxyl groups, which can interact with copper ions through hydrogen bonds, so that the surface of the bacterial cellulose is enriched with copper ions. After the addition of sodium sulfide, sulfur ions combine with copper ions to obtain copper sulfide-loaded bacterial cellulose. After the reaction is completed, the product is washed with deionized water, and then frozen (frozen at -40 to -20°C for 5-12 h), and freeze-dried (freeze-dried at -60 to -40°C for 8-15 h) to obtain copper sulfide-loaded bacterial cellulose. The obtained copper sulfide-loaded bacterial cellulose is dispersed in water to obtain a copper sulfide-loaded bacterial cellulose dispersion solution; 3) Preparation of a methyltrimethoxysilane sol: methyltrimethoxysilane is added to an acetic acid solution and stirred uniformly to obtain a methyltrimethoxysilane sol; 4) The polyvinyl alcohol solution obtained in step 1), the copper sulfide-loaded bacterial cellulose dispersion solution obtained in step 2) and the methyltrimethoxysilane sol obtained in step 3) are mixed and reacted, and then sequentially subjected to pre-freezing treatment, freeze-drying and heat treatment to obtain a photo-thermal hydrophobic composite aerogel for crude oil adsorption.

[0009] According to the above scheme, the number average molecular weight of the polyvinyl alcohol in step 1) is 8W-30W, and the concentration of the polyvinyl alcohol solution is 0.5-1wt%. The specific stirring time of the polyvinyl alcohol in water is 8-12 h.

[0010] According to the above scheme, the concentration of the ammonia solution in step 2) is 5-9mol / L, the concentration of the copper sulfate solution is 10-80mmol / L, and the volume ratio of the ammonia solution to the copper sulfate solution is 1-7:20.

[0011] According to the above scheme, the concentration of the bacterial cellulose dispersion solution in step 2) is 0.4-0.8 wt%, the concentration of the sodium sulfide solution is 3-8 mol / L, and the mass ratio of copper sulfate in the copper sulfate solution, bacterial cellulose in the bacterial cellulose dispersion solution, and sodium sulfide in the sodium sulfide solution is 0.08-0.64:1:0.35-0.94.

[0012] According to the above scheme, the concentration of the copper sulfide-loaded bacterial cellulose dispersion solution in step 2) is 0.2-0.6 wt%.

[0013] According to the above scheme, the concentration of the acetic acid solution in step 3) is 4-6 mmol / L, and the volume ratio of methyltrimethoxysilane to the acetic acid solution is 1:2-4.

[0014] According to the above scheme, the volume ratio of the polyvinyl alcohol solution, the copper sulfide-loaded bacterial cellulose dispersion solution, and the methyltrimethoxysilane sol in step 4) is 50:50:1-8.

[0015] According to the above scheme, the reaction conditions in step 4) are as follows: the reaction is carried out at room temperature (15-35℃) for 1-3 h.

[0016] According to the above scheme, the pre-freezing treatment process conditions in step 4) are as follows: freezing at-40--20℃ for 5-12 h, or directional freezing for 5-20 min after injection into a container with a copper rod immersed in liquid nitrogen at the bottom. The directional freezing method is preferred, which can construct regularly arranged directional channels and provide efficient transmission paths for the rapid adsorption of oil substances, showing excellent adsorption performance.

[0017] According to the above scheme, the freeze-drying process conditions in step 4) are as follows: the freeze-drying temperature is-60--40℃, and the freeze-drying time is 12-36 h.

[0018] According to the above scheme, the heat treatment process conditions in step 4) are as follows: heating at 80-100℃ for 5-10 h.

[0019] The third aspect of the present application provides the use of the above-mentioned photothermal hydrophobic composite aerogel for crude oil adsorption as an adsorbent in oil-water separation.

[0020] The application selects the copper sulfide loaded bacterial cellulose and polyvinyl alcohol as light-absorbing material and matrix material respectively, and methyltrimethoxysilane as a crosslinking agent, the surface of the copper sulfide loaded bacterial cellulose and polyvinyl alcohol is rich in hydroxyl groups, and stable hydrogen bond interaction is easily formed between the two, the silanol produced by the hydrolysis of methyltrimethoxysilane can interact with the hydroxyl groups on the bacterial cellulose and polyvinyl alcohol, and is used for constructing a crosslinked three-dimensional network structure, so that the obtained aerogel shows regularly arranged lamellar directional channels or rich interconnected pores, in addition, methyltrimethoxysilane is also used as a hydrophobic agent, after heat treatment, the "hard" polymethylsilsesquioxane generated by the polycondensation of methyltrimethoxysilane is crosslinked with the "soft" copper sulfide loaded bacterial cellulose and polyvinyl alcohol to form a hard-soft interlocking network, and the structure can significantly enhance the elastic properties of the aerogel, and the presence of a large number of hydrophobic groups (-CH3) endows the aerogel with hydrophobicity.

[0021] The introduction of copper sulfide in the application endows the aerogel with excellent photothermal properties, which is beneficial to improve the flowability of high-viscosity crude oil, realize in-situ solar-driven rapid adsorption of crude oil, and solve the problem that the traditional polyvinyl alcohol-based adsorption material is not easy to remove high-viscosity crude oil.

[0022] The application has the advantages that: 1, the photothermal hydrophobic composite aerogel has excellent hydrophobicity (water contact angle is as high as 142.1°) and elasticity, has a large adsorption capacity for oily substances, has excellent photothermal properties, can be used as an adsorbent for crude oil recovery, can be repeatedly used, and has practical popularization and application value. 2, the preparation method realizes the integration of the hydrophobicity, elasticity and photothermal properties of the aerogel through one-pot reaction, the steps are simple, and the synthesis and modification steps are reduced, so that the economic and environmental benefits are remarkable. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The comparison figure of the photothermal hydrophobic composite aerogel prepared for example 1, example 3 and comparative example 1 is placed on the water surface; Figure 2 The water contact angle photo of the photothermal hydrophobic composite aerogel prepared for example 1 and example 3; Figure 3 The adsorption performance of the photothermal hydrophobic composite aerogel prepared for example 1 on the oil-water mixture is tested on the oil-water mixture adsorption performance test figure; Figure 4 The cross-section scanning electron microscope photo of the photothermal hydrophobic composite aerogel prepared for example 1; Figure 5 The cross-section scanning electron microscope photo of the photothermal hydrophobic composite aerogel prepared for example 3; Figure 6Photos of the photo-thermal hydrophobic composite aerogel prepared for Example 1 and Comparative Example 1 compressed and released under a 200g weight; Figure 7 Cycle stress-strain curve graph of the photo-thermal hydrophobic composite aerogel prepared for Example 1 tested under 60% constant strain; Figure 8 Comparison graph of the adsorption capacity of the photo-thermal hydrophobic composite aerogels prepared for Examples 1-6 to low viscosity crude oil; Figure 9 Adsorption performance test graph of the photo-thermal hydrophobic composite aerogel prepared for Example 1 to different oils; Figure 10 Temperature change curve graph of the surface of the photo-thermal hydrophobic composite aerogel prepared for Example 1, Example 3 and Comparative Example 2 under irradiation of 2.0kW·m -2 Figure 11 (a) Temperature change curve graph of the surface of the photo-thermal hydrophobic composite aerogel prepared for Example 1 under irradiation of different simulated sunlight intensities, (b) Comparison graph of the temperature changes of the top, side and bottom of the photo-thermal hydrophobic composite aerogel prepared for Example 1 under irradiation of 2.0kW·m -2 Figure 12 Adsorption performance test graph of the photo-thermal hydrophobic composite aerogels prepared for Example 1, Example 3 to high viscosity crude oil; Figure 13 Cycle adsorption performance test graph of the photo-thermal hydrophobic composite aerogel prepared for Example 1 to high viscosity crude oil. DETAILED DESCRIPTION

[0024] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below with reference to the accompanying drawings.

[0025] The number average molecular weight of the polyvinyl alcohol used in the example of the present application is 195000; the bacterial cellulose dispersion liquid used is purchased from Guilin Qihong Technology Co., Ltd.

[0026] Example 1 A photo-thermal hydrophobic composite aerogel, the specific preparation steps are as follows: 1) Add polyvinyl alcohol into water at 90℃, and stir to obtain a polyvinyl alcohol solution with a concentration of 0.8wt%; ​​2) 500 μL of ammonia solution (7 mol / L) was dropped into 10 mL of copper sulfate solution (40 mmol / L) to obtain a deep blue copper ammonia complex ion solution, and then 25 mL of the bacterial cellulose dispersion (0.8 wt%) was added into the copper ammonia complex ion solution, and the mixture was stirred at room temperature for 2 h, and then 300 μL of sodium sulfide solution (4 mol / L) was added, and the mixture was stirred for 3 h. After the reaction was completed, the obtained product was washed with deionized water, and then was frozen in a refrigerator at -20 °C for 10 h, and then was freeze-dried at -50 °C for 12 h to obtain the copper sulfide-loaded bacterial cellulose, which was dispersed in deionized water to obtain a copper sulfide-loaded bacterial cellulose dispersion with a concentration of 0.4 wt%; 3) 2 mL of methyltrimethoxysilane was mixed with 6 mL of acetic acid solution (5 mmol / L) by magnetic stirring for 30 min to obtain a methyltrimethoxysilane sol; 4) 5 mL of the copper sulfide-loaded bacterial cellulose dispersion obtained in step 2) was mixed with 5 mL of the polyvinyl alcohol solution obtained in step 1) by magnetic stirring for 30 min, and then 500 μL of the methyltrimethoxysilane sol obtained in step 3) was added, and the mixture was stirred for 2 h. The obtained mixture was poured into a mold, and then the mold was placed on a copper rod with the bottom end immersed in liquid nitrogen for directional freezing for 10 min. The obtained solid was freeze-dried at -50 °C for 24 h, and then was heated in an oven at 80 °C for 5 h to obtain the photo-thermal hydrophobic composite aerogel.

[0027] Example 2 A photo-thermal hydrophobic composite aerogel, the difference between the preparation method and example 1 is that the concentration of the copper sulfide-loaded bacterial cellulose dispersion in step 2) is 0.2 wt%, and the directional freezing in step 4) is replaced by freezing in a refrigerator at -20 °C for 10 h, and the other steps are the same.

[0028] Example 3 A photo-thermal hydrophobic composite aerogel, the difference between the preparation method and example 1 is that the directional freezing in step 4) is replaced by freezing in a refrigerator at -20 °C for 10 h, and the other steps are the same.

[0029] Example 4 A photo-thermal hydrophobic composite aerogel, the difference between the preparation method and example 1 is that the concentration of the copper sulfide-loaded bacterial cellulose dispersion in step 2) is 0.6 wt%, and the directional freezing in step 4) is replaced by freezing in a refrigerator at -20 °C for 10 h, and the other steps are the same.

[0030] Example 5 A photo-thermal hydrophobic composite aerogel, the difference between the preparation method and example 3 is that the volume of the methyltrimethoxysilane sol added in step 4) is 400 μL, and the other steps are the same.

[0031] Example 6 A photo-thermal hydrophobic composite aerogel, the difference between the preparation method and Example 3 is that the volume of methyltrimethoxysilane sol added in step 4) is 600 μL, and the rest of the steps are the same.

[0032] Comparative Example 1 The difference between this comparative example and Example 1 is that in step 3), no methyltrimethoxysilane sol is added, and the rest is the same as Example 1.

[0033] Comparative Example 2 The difference between this comparative example and Example 1 is that in step 3), the same mass concentration and volume of bacterial cellulose dispersion is used instead of copper sulfide loaded bacterial cellulose dispersion, and the rest is the same as Example 1.

[0034] Comparative Example 3 Replace methyltrimethoxysilane in Example 1 with an equal volume of 3- aminopropyltriethoxysilane or vinyltriethoxysilane, and the rest of the conditions are the same as Example 1.

[0035] When 3-aminopropyltriethoxysilane is selected, the obtained hydrogel does not have hydrophobicity. When vinyltriethoxysilane is selected, the obtained hydrogel has poor elasticity.

[0036] As shown in Figure 1 , the aerogels prepared in Comparative Example 1, Example 1 and Example 3 are placed on the water surface at the same time, it can be observed that the aerogels prepared in Example 1 and Example 3 float on the water surface and are almost not wetted by water, showing hydrophobicity. The aerogel prepared in Comparative Example 1 quickly absorbs water after contacting with water and soon sinks into water, showing hydrophilicity, which indicates that the addition of methyltrimethoxysilane sol provides hydrophobicity for the aerogel. At the same time, it can be seen that the volume of the aerogels prepared in Example 1 and Example 3 is significantly larger than that of Comparative Example 1, and the aerogel constructed by adding methyltrimethoxysilane sol has larger porosity, indicating that methyltrimethoxysilane sol can improve the structure of the aerogel.

[0037] As shown in Figure 2 , the water contact angle photos of the photo-thermal hydrophobic composite aerogels prepared in Example 1 and Example 3 are shown, and the water contact angles thereof are measured to be 142.1° and 140.9° respectively, indicating that the aerogels prepared in Example 1 and Example 3 both have good hydrophobicity.

[0038] The adsorption performance of the photo-thermal hydrophobic composite aerogel prepared in Example 1 on oil-water mixture is tested, and the test process photo is shown in Figure 3 Figure 3 ​(a) For the water absorption experiment, light oil (toluene) was added to water to obtain an oil-water mixture (oil-water volume ratio of 1:100). The photothermal hydrophobic composite aerogel prepared in Example 1 was placed on the oil layer with tweezers, and it was observed that toluene was quickly adsorbed by the aerogel. Figure 3 (b) For the underwater oil absorption experiment, heavy oil (dichloromethane) was added to water to obtain an oil-water mixture (oil-water volume ratio of 1:100). The photothermal hydrophobic composite aerogel prepared in Example 1 was immersed in the oil-water mixture using tweezers and placed above the oil layer. It was observed that dichloromethane was quickly adsorbed by the aerogel. The test results show that the photothermal hydrophobic composite aerogel prepared in Example 1 can selectively adsorb oil in the oil-water mixture.

[0039] like Figure 4 The image shown is a cross-sectional scanning electron microscope image of the photothermal hydrophobic composite aerogel prepared in Example 1. It can be seen that the composite aerogel is formed by a regular arrangement of multiple layers, with each layer supported by composite fiber filaments. The spacing between each layer is about 20~60μm, and directional channels are formed between each layer, which can provide an efficient transport path for the rapid adsorption of oily substances.

[0040] Figure 5 The image shown is a cross-sectional scanning electron microscope image of the photothermal hydrophobic composite aerogel prepared in Example 3. It can be seen that the composite aerogel has abundant interconnected pores.

[0041] like Figure 6 The images shown are photographs of the photothermal hydrophobic composite aerogels prepared in Example 1 and Comparative Example 1 under compression and release under a 200g weight. It can be observed that the composite aerogel prepared in Example 1 can recover its original shape after being compressed by a 200g weight, indicating that the aerogel has good elasticity. However, the composite aerogel prepared in Comparative Example 1 cannot recover its original shape after being compressed by a 200g weight, indicating that the addition of methyltrimethoxysilane sol increases the elasticity of the aerogel.

[0042] The cyclic stress-strain curves of the photothermal-hydrophobic composite aerogel prepared in Example 1 under a constant strain of 60% are shown in the figure below. Figure 7 As shown, the composite aerogel exhibits excellent compressive resilience performance. After the first cycle, the height deformation rate is close to 0 under constant strain of 60%. After 10 stress-relief cycles, the height recovers to 93.6% of the original height. The photothermal-hydrophobic composite aerogels prepared in Examples 1-6 were placed in low-viscosity crude oil (purchased from Shaanxi Yanchang Petroleum Company, with a viscosity of 24.7 mPa·s at room temperature) to test their adsorption performance on the low-viscosity crude oil. Figure 8The figures show a comparison of the adsorption performance of the photothermal hydrophobic composite aerogels prepared in Examples 1-6 for low-viscosity crude oil. It can be seen that the composite aerogel prepared in Example 1 has an adsorption capacity of up to 63.0 g / g for low-viscosity crude oil at room temperature, which is superior to the composite aerogel in Example 3, indicating that the directional freezing method can improve the adsorption performance of the composite aerogel. The composite aerogel in Example 3 has a higher adsorption capacity for low-viscosity crude oil than the composite aerogels in Examples 5 and 6, indicating that too much or too little methyltrimethoxysilane content is detrimental to the adsorption performance of the composite aerogel. A comparison of the composite aerogels in Examples 2-4 shows that the composite aerogel prepared in Example 3 has the highest adsorption capacity for low-viscosity crude oil, indicating that the content of copper sulfide-loaded bacterial cellulose affects the oil absorption effect of the aerogel. This is because too little copper sulfide-loaded bacterial cellulose leads to a smaller aerogel volume and reduced oil storage space, resulting in a reduced adsorption capacity; while too much copper sulfide-loaded bacterial cellulose leads to a denser aerogel structure, causing pore blockage and reducing the oil storage space, thus reducing the adsorption capacity.

[0043] The adsorption performance of the photothermal-hydrophobic composite aerogel prepared in Example 1 for different oils was tested. At room temperature, the photothermal-hydrophobic composite aerogel prepared in Example 1 was placed in chloroform, dichloromethane, toluene, n-hexane, low-viscosity crude oil (purchased from Shaanxi Yanchang Petroleum Company, viscosity at room temperature: 24.7 mPa·s), olive oil, and soybean oil, respectively. The adsorption capacity test results are as follows: Figure 9 As shown, it has the lowest adsorption capacity for n-hexane (45.5 g / g) and the highest adsorption capacity for chloroform (105.6 g / g). Furthermore, the adsorption of chloroform reaches adsorption equilibrium within 1 second, indicating that the composite aerogel prepared in Example 1 has good oil absorption capacity.

[0044] like Figure 10 The images show photothermal hydrophobic composite aerogels prepared in Examples 1, 3, and 2 at 2kW·m. -2 The surface temperature change curve of the composite aerogel under simulated sunlight irradiation for 3 minutes shows that the surface temperatures of the composite aerogels prepared in Example 1 and Example 3 reach 110.1℃ and 110.6℃ respectively within 3 minutes, which are significantly higher than the surface temperature of Comparative Example 2, indicating that the composite aerogels prepared in Example 1 and Example 3 have excellent photothermal conversion performance.

[0045] like Figure 11 (a) shows the photothermal hydrophobic composite aerogel prepared in Example 1 under different simulated solar light intensities (0.5 kW·m). -2 1.0kW・m -2 1.5kW・m -2 2.0kW・m -2) The surface temperature change curve of the composite aerogel irradiated for 3 minutes can be observed to gradually increase from 53.1℃ at 0.5kW・m -2 to 110.1℃ as the simulated sunlight intensity increases. As Figure 11 (b) shows the temperature change comparison chart of the top, side and bottom of the photothermal hydrophobic composite aerogel (2 cm in diameter and 1 cm in height) prepared in Example 1 under the irradiation of 2.0kW・m -2 The temperature of the top, side and bottom of the composite aerogel is different because the heat radiation is not uniformly transmitted in the internal channels of the aerogel due to the fact that the simulated sunlight only irradiates the top surface of the composite aerogel. Although there is no direct irradiation, the side and bottom temperatures of the composite aerogel still reach 67.0℃ and 40.5℃, respectively, after 3 minutes of irradiation on the top. The composite aerogel prepared in Example 1 was placed under the irradiation of 2.0kW・m -2 The surface temperature change of the composite aerogel was tested for 5 cycles of turning on and off the light every 3 minutes, and the test chart is shown in Figure 11 (c) can be observed. The surface temperature change curve of the composite aerogel is almost the same, indicating that it has good photothermal performance and photothermal stability, which is conducive to the adsorption of high viscosity crude oil.

[0046] The adsorption performance of the photothermal hydrophobic composite aerogel prepared in Examples 1 and 3 to high viscosity crude oil was tested. The photothermal hydrophobic composite aerogel prepared in Examples 1 and 3 was placed on the surface of a mixture of high viscosity crude oil (purchased from Shaanxi Yanchang Petroleum Company, viscosity at room temperature is 6.2×10 3 mPa s) and water (oil-water volume ratio is 1:4), and the test process photos are shown in Figure 12 (a) is the adsorption process chart of the composite aerogel prepared in Examples 1 and 3 to high viscosity crude oil under no light irradiation. It can be observed that the aerogel remains almost static without light irradiation, and there is no obvious adsorption behavior even after 60 min. (b) is the adsorption process chart of the composite aerogel prepared in Examples 1 and 3 to high viscosity crude oil under the irradiation of 2.0kW・m -2 It can be found that the composite aerogel gradually sinks into the high viscosity crude oil, and the photothermal hydrophobic composite aerogel prepared in Example 1 takes a shorter time (7 min) to immerse in the crude oil and almost reaches equilibrium, indicating that its directional channel structure is conducive to accelerating the adsorption of high viscosity crude oil.

[0047] The light-heat hydrophobic composite aerogel (a disc with a diameter of 2 cm and a height of 1 cm) prepared in Example 1 was used to test the cyclic adsorption performance of high-viscosity crude oil. The composite aerogel prepared in Example 1 was placed on the surface of high-viscosity crude oil (purchased from Shaanxi Yanchang Petroleum Company, with a viscosity of 6.2 x 10 3 mPa s at room temperature) and was irradiated for 7 min under a light intensity of 2.0 kW·m -2 Then, the aerogel was squeezed under a strain of 75%, and the above adsorption-squeezing operation was repeated for 9 cycles. The adsorption capacity and total adsorption capacity of 10 adsorptions were tested, and the test results are shown in Table 1. Figure 13 As shown in Table 1, it can be observed that the first adsorption capacity of the composite aerogel can reach 52.2 g / g, and the adsorption capacity retention rate of the composite aerogel after 10 adsorption-squeezing cycles is still as high as 85% (a). The oil squeezed out each time was collected, and a total of 13.8 g of high-viscosity crude oil was recovered after 10 squeezing cycles (b), which shows good reusability.

[0048] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A photothermal hydrophobic composite aerogel for crude oil adsorption, characterized in that, It is obtained by mixing and reacting polyvinyl alcohol solution, bacterial cellulose dispersion loaded with copper sulfide and methyltrimethoxysilane sol, followed by pre-freezing treatment, freeze drying and heat treatment.

2. The photothermal hydrophobic composite aerogel for crude oil adsorption according to claim 1, characterized in that, The water contact angle of the polyvinyl alcohol-based photothermal hydrophobic composite aerogel is 120~160°.

3. A method for preparing a photothermal hydrophobic composite aerogel for crude oil adsorption as described in claim 1 or 2, characterized in that, The specific steps are as follows: 1) Preparation of polyvinyl alcohol solution: Add polyvinyl alcohol to water at 85~95℃ and stir to dissolve to obtain polyvinyl alcohol solution; 2) Preparation of copper sulfide-loaded bacterial cellulose dispersion: Ammonia solution was added to copper sulfate solution and stirred vigorously at room temperature to obtain a deep blue copper ammonia complex ion solution. Bacterial cellulose dispersion was added to the obtained copper ammonia complex ion solution and stirred at room temperature for 1-4 hours. Then sodium sulfide solution was added and stirred at room temperature for 2-4 hours. After the reaction was completed, the product was washed with deionized water and then frozen and freeze-dried to obtain copper sulfide-loaded bacterial cellulose. The obtained copper sulfide-loaded bacterial cellulose was then dispersed in water to obtain copper sulfide-loaded bacterial cellulose dispersion. 3) Preparation of methyltrimethoxysilane sol: Add methyltrimethoxysilane to an acetic acid solution and stir until homogeneous to obtain methyltrimethoxysilane sol; 4) The polyvinyl alcohol solution obtained in step 1), the bacterial cellulose dispersion loaded with copper sulfide obtained in step 2), and the methyltrimethoxysilane sol obtained in step 3) were mixed and reacted, and then subjected to pre-freezing treatment, freeze drying and heat treatment in sequence to obtain polyvinyl alcohol-based photothermal hydrophobic composite aerogel.

4. The preparation method of the photothermal hydrophobic composite aerogel for crude oil adsorption according to claim 3, characterized in that, Step 1) The number average molecular weight of the polyvinyl alcohol is 8W~30W, and the concentration of the polyvinyl alcohol solution is 0.5~1wt%.

5. The preparation method of the photothermal hydrophobic composite aerogel for crude oil adsorption according to claim 3, characterized in that, Step 2) The concentration of the ammonia solution is 5~9 mol / L, the concentration of the copper sulfate solution is 10~80 mmol / L, and the volume ratio of the ammonia solution to the copper sulfate solution is 1~7:

20.

6. The method for preparing the photothermal hydrophobic composite aerogel for crude oil adsorption according to claim 3, characterized in that, In step 2), the concentration of the bacterial cellulose dispersion is 0.4~0.8wt%, the concentration of the sodium sulfide solution is 3~8mol / L, and the mass ratio of copper sulfate in the copper sulfate solution, bacterial cellulose in the bacterial cellulose dispersion, and sodium sulfide in the sodium sulfide solution is 0.08~0.64:1:0.35~0.94; in step 2), the concentration of the copper sulfide-loaded bacterial cellulose dispersion is 0.2~0.6wt%.

7. The method for preparing the photothermal hydrophobic composite aerogel for crude oil adsorption according to claim 3, characterized in that, Step 3) The concentration of the acetic acid solution is 4~6 mmol / L, and the volume ratio of the methyltrimethoxysilane to the acetic acid solution is 1:2~4.

8. The method for preparing the photothermal hydrophobic composite aerogel for crude oil adsorption according to claim 3, characterized in that, Step 4) The volume ratio of the polyvinyl alcohol solution, the bacterial cellulose dispersion loaded with copper sulfide, and the methyltrimethoxysilane sol is 50:50:1~8.

9. The method for preparing the photothermal hydrophobic composite aerogel for crude oil adsorption according to claim 3, characterized in that, Step 4) Reaction conditions: react at room temperature for 1~3h; Step 4) Pre-freezing process conditions: freeze at -40~-20℃ for 5~12h, or after being injected into a container, place it on a copper rod with the bottom end immersed in liquid nitrogen and freeze directionally for 5~20min; Step 4) Freeze-drying process conditions: freeze-drying temperature is -60~-40℃, freeze-drying time is 12~36h; Step 4) Heat treatment process conditions: heat at 80~100℃ for 5~10h.

10. The application of the photothermal hydrophobic composite aerogel for crude oil adsorption as described in claim 1 or 2 as an adsorbent in oil-water separation.

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