Preparation method and application of composite aerogel for photothermal evaporator
By crosslinking sepiolite/nanocarbon with vermiculite nanosheets to prepare composite aerogels, the problems of high energy consumption and salt deposition in existing seawater desalination technologies have been solved, achieving efficient solar evaporation and dye wastewater treatment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2023-12-01
- Publication Date
- 2026-06-12
AI Technical Summary
Existing seawater desalination technologies are energy-intensive, use expensive materials, and are difficult to apply on a large scale. Furthermore, salt deposition in water channels leads to a decrease in evaporation performance.
A composite aerogel was prepared by mixing sepiolite/nanocarbon materials with vermiculite nanosheets and then freeze-drying via ion crosslinking. This aerogel was used in a photothermal evaporator, utilizing vermiculite nanosheets as a framework to reduce the amount of carbon materials used.
It achieves highly efficient solar evaporation, has strong salt repulsion, and increases the evaporation rate by 548.7%. It is suitable for the treatment of high-concentration brine and dye wastewater, and the preparation method is simple and environmentally friendly.
Smart Images
Figure CN117427576B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of interfacial evaporation water treatment technology, and more specifically, relates to a method for preparing vermiculite / sepiolite / nanocarbon composite aerogel for photothermal evaporators and its application. Background Technology
[0002] Water is one of the most abundant resources on Earth, covering 71% of its surface. However, freshwater resources available for direct human use and drinking remain extremely scarce. To address this challenge, various technologies are being developed, such as membrane distillation, electrodialysis, and reverse osmosis. However, these seawater desalination technologies are energy-intensive and use expensive materials, making it difficult to meet the basic water needs of remote areas and developing countries.
[0003] As Chen et al. mentioned in "Challenges and Opportunities of Solar Evaporation," in recent years, solar-driven interfacial evaporation seawater desalination technology has attracted increasing attention and rapid development due to its use of clean and renewable solar energy and its excellent photothermal conversion efficiency. Guan et al., in "Carbon Materials for Solar Evaporation and Seawater Desalination," mentioned that common photothermal materials used in solar interfacial evaporation mainly include plasma metals, carbon-based materials, semiconductors, and polymer materials, as well as mixtures thereof. However, the preparation methods are complex, cannot be mass-produced, and lack universality. Furthermore, as seawater evaporates, salt deposits in the water channels, clogging the water supply path and inevitably reducing evaporation performance.
[0004] Therefore, it is of great significance to develop a simple assembly method to manufacture a three-dimensional photothermal evaporator with good salt repulsion using low-cost raw materials in order to achieve efficient solar evaporation. Summary of the Invention
[0005] The purpose of this invention is to develop a method for preparing composite aerogels for photothermal evaporators and their applications.
[0006] The technical solution of this invention:
[0007] A method for preparing a composite aerogel for photothermal evaporators involves mixing a sepiolite / nanocarbon material dispersion and a vermiculite nanosheet dispersion in a certain proportion, followed by ion crosslinking and freeze-drying to obtain the composite aerogel for photothermal evaporation.
[0008] Includes the following steps:
[0009] (1) Preparation of sepiolite / nanocarbon dispersion
[0010] Sepiolite powder was mixed with deionized water and dispersed using an ultrasonic cell disruptor. Then, nano-carbon material powder was added to the sepiolite dispersion and dispersed using an ultrasonic cell disruptor. Finally, a sepiolite / nano-carbon dispersion was obtained with a mass ratio of sepiolite to nano-carbon of 0.75-7 and a concentration of 10 mg / mL of sepiolite in the sepiolite / nano-carbon dispersion.
[0011] (2) Preparation of vermiculite dispersion
[0012] Vermiculite was mixed with a saturated sodium chloride solution and placed in a reaction vessel. The mass ratio of vermiculite to saturated sodium chloride was controlled at 0.01-0.03. The mixture was then hydrothermally reacted at 105-125℃ for 1-3 hours. Afterward, the mixture was filtered and washed 4-6 times with deionized water. Then, 2 mol / L LiCl solution was added, and the mass ratio of vermiculite to LiCl solution was controlled at 0.01-0.03. The mixture was then hydrothermally reacted at 105-125℃ for 1-3 hours. Finally, the mixture was filtered and washed with deionized water to obtain expanded vermiculite. The expanded vermiculite was mixed with deionized water and homogenized at 20000-22000 rpm for 15-20 minutes. The resulting mixture was then centrifuged at 300 rpm for 60 minutes to remove impurities. The impurity-removed vermiculite dispersion was then concentrated by centrifugation to obtain a vermiculite dispersion with a concentration of 6-40 mg / mL.
[0013] (3) Preparation of composite aerogel
[0014] Vermiculite dispersion was mixed with sepiolite / nanocarbon dispersion, and the mass ratio of vermiculite to sepiolite was controlled at 3-4. AlCl3 solution was then added for cross-linking to obtain vermiculite / sepiolite / nanocarbon composite hydrogel. The vermiculite / sepiolite / nanocarbon composite hydrogel was frozen in a refrigerator for 2-3 hours and then dried in a freeze dryer for 48 hours to obtain vermiculite / sepiolite / nanocarbon composite aerogel.
[0015] Using metal cations (Al) 3+ ,Fe 3+ Ca 2+ Crosslinking vermiculite nanosheets to construct an aerogel framework.
[0016] Nano-carbon accounts for 3-21% of the mass of vermiculite / sepiolite / nano-carbon composite hydrogels.
[0017] The mass ratio of vermiculite dispersion to 0.5 mol / L AlCl3 solution was 120:0.133-0.350.
[0018] Nanocarbon includes multi-walled carbon nanotubes, carbon black, graphene, and graphite.
[0019] Application of vermiculite / sepiolite / nanocarbon composite aerogel obtained by the above preparation method in the treatment of seawater and dye wastewater.
[0020] The beneficial effects of this invention are:
[0021] (1) This invention uses sepiolite instead of surfactant to disperse carbon materials, which is clean and pollution-free, simple, and can be prepared in large quantities, making it universally applicable. It is then mixed with vermiculite nanosheet dispersion, using vermiculite nanosheets as the aerogel framework, which greatly reduces the use of expensive carbon materials.
[0022] (2) Under standard sunlight irradiation, the water evaporation rate of the vermiculite / sepiolite / carbon-based composite aerogel in simulated seawater with 3.5 wt% NaCl reached 2.53 kg / m³. -2 h -1 Compared to water that evaporates directly without using composite aerogel, the evaporation rate is 548.7% higher.
[0023] (3) The composite aerogel preparation method of the present invention is simple and universal, and can be used to treat high-concentration salt water and dye wastewater, etc. Attached Figure Description
[0024] Figure 1 The images shown are SEM images of the products of this invention, where a is a SEM image of sepiolite / carbon nanotube film; and b is a VSC-17 SEM image.
[0025] Figure 2 The absorption spectrum of VSC-17 in the 300-2000 nm solar wavelength range is shown.
[0026] Figure 3 The diagram shows the water evaporation rate of different aerogels (VSC-3, VSC-12, VSC-17, VSC-21) of the present invention under a standard solar radiation intensity in simulated seawater.
[0027] Figure 4 The evaporation rate of different aerogels (VSGT-17, VSGN-17, VSCB-17) under a standard solar radiation intensity in simulated seawater is shown in the figure.
[0028] Figure 5 The above are ultraviolet absorption spectra of the present invention, wherein a is the ultraviolet absorption spectrum of the VSC-17 evaporation dye wastewater (methyl orange MO) solution before and after evaporation; b is the ultraviolet absorption spectrum of the VSC-17 evaporation dye wastewater (methylene blue MB) solution before and after evaporation. Detailed Implementation
[0029] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.
[0030] Example 1
[0031] A method for preparing vermiculite / sepiolite / carbon-based composite aerogel for photothermal evaporators includes the following steps:
[0032] (1) Preparation of vermiculite dispersion and sepiolite / carbon nanotube dispersion
[0033] 3.6 g of vermiculite was mixed with 100 mL of saturated NaCl solution and placed in a reaction vessel. The mixture was hydrothermally reacted at 110 °C for 2 h. After cooling, the mixture was filtered and washed with deionized water to remove the NaCl. Then, 100 mL of 2 mol / L LiCl solution was added, and the reaction was continued at 110 °C for another 2 h. After cooling, the mixture was centrifuged and washed 4-5 times with deionized water to remove LiCl. The washed expanded vermiculite was then added to deionized water and homogenized at 20,000 rpm for 15 min. The resulting vermiculite dispersion was centrifuged at 300 rpm for 60 min to remove impurities. The purified vermiculite dispersion was then concentrated by centrifuging at 7,000 rpm for 60 min to obtain a 30 mg / mL vermiculite dispersion.
[0034] 1g of sepiolite powder was mixed with 100mL of deionized water and dispersed for 30min using an ultrasonic cell disruptor to obtain a 10mg / mL sepiolite dispersion. Then, 1g of multi-walled carbon nanotube powder was added to 100mL of the 10mg / mL sepiolite dispersion and dispersed for 30min using an ultrasonic cell disruptor to obtain a 100mL sepiolite / carbon nanotube dispersion (mass ratio of sepiolite:carbon nanotube = 6.5, sepiolite dispersion concentration 10mg / mL).
[0035] (2) Preparation of vermiculite / sepiolite / carbon nanotube composite aerogel
[0036] Vermiculite dispersion was mixed with sepiolite / carbon nanotube dispersion at a mass ratio of vermiculite:sepiolite = 4. AlCl3 solution was added for crosslinking, with a vermiculite:FeCl3 mass ratio of 120:0.2. The resulting hydrogel was frozen at -18℃ for 2 hours, and then freeze-dried at -45℃ and 8Pa for 48 hours to obtain aerogel. The carbon nanotubes accounted for 3% of the total mass of the aerogel.
[0037] Example 2
[0038] (1) Preparation of vermiculite dispersion and sepiolite / carbon nanotube dispersion
[0039] 3.6 g of vermiculite was mixed with 100 mL of saturated NaCl solution and placed in a reaction vessel. The mixture was hydrothermally reacted at 110 °C for 2 h. After cooling, the mixture was filtered and washed with deionized water to remove the NaCl. Then, 100 mL of 2 mol / L LiCl solution was added, and the reaction was continued at 110 °C for another 2 h. After cooling, the mixture was centrifuged and washed 4-5 times with deionized water to remove LiCl. The washed expanded vermiculite was then added to deionized water and homogenized at 20,000 rpm for 15 min. The resulting vermiculite dispersion was centrifuged at 300 rpm for 60 min to remove impurities. The purified vermiculite dispersion was then concentrated by centrifuging at 7,000 rpm for 60 min to obtain a 30 mg / mL vermiculite dispersion.
[0040] 1g of sepiolite powder was mixed with 100mL of deionized water and dispersed for 30min using an ultrasonic cell disruptor to obtain a 10mg / mL sepiolite dispersion. Then, 1g of multi-walled carbon nanotube powder was added to 100mL of the 10mg / mL sepiolite dispersion and dispersed for 30min using an ultrasonic cell disruptor to obtain a 100mL sepiolite / carbon nanotube dispersion (mass ratio of sepiolite:carbon nanotube = 1.46, sepiolite dispersion concentration 10mg / mL).
[0041] (2) Preparation of vermiculite / sepiolite / carbon nanotube composite aerogel
[0042] Vermiculite dispersion was mixed with sepiolite / carbon nanotube dispersion at a mass ratio of vermiculite:sepiolite = 4. AlCl3 solution was added for crosslinking, with a vermiculite:AlCl3 mass ratio of 120:0.133. The resulting hydrogel was frozen at -18℃ for 2 hours, and then freeze-dried at -45℃ and 8Pa for 48 hours to obtain aerogel. Carbon nanotubes accounted for 12% of the total mass of the aerogel.
[0043] Example 3
[0044] (1) Preparation of vermiculite dispersion and sepiolite / carbon nanotube dispersion
[0045] 3.6 g of vermiculite was mixed with 100 mL of saturated NaCl solution and placed in a reaction vessel. The mixture was hydrothermally reacted at 110 °C for 2 h. After cooling, the mixture was filtered and washed with deionized water to remove the NaCl. Then, 100 mL of 2 mol / L LiCl solution was added, and the reaction was continued at 110 °C for another 2 h. After cooling, the mixture was centrifuged and washed 4-5 times with deionized water to remove LiCl. The washed expanded vermiculite was then added to deionized water and homogenized at 20,000 rpm for 15 min. The resulting vermiculite dispersion was centrifuged at 300 rpm for 60 min to remove impurities. The purified vermiculite dispersion was then concentrated by centrifuging at 7,000 rpm for 60 min to obtain a 30 mg / mL vermiculite dispersion.
[0046] 1g of sepiolite powder was mixed with 100mL of deionized water and dispersed for 30min using an ultrasonic cell disruptor to obtain a 10mg / mL sepiolite dispersion. Then, 1g of multi-walled carbon nanotube powder was added to 100mL of the 10mg / mL sepiolite dispersion and dispersed for 30min using an ultrasonic cell disruptor to obtain a 100mL sepiolite / carbon nanotube dispersion (mass ratio of sepiolite:carbon nanotube = 1, sepiolite dispersion concentration 10mg / mL).
[0047] (2) Preparation of vermiculite / sepiolite / carbon nanotube composite aerogel
[0048] Vermiculite dispersion was mixed with sepiolite / carbon nanotube dispersion at a mass ratio of vermiculite:sepiolite = 4. AlCl3 solution was added for crosslinking, with a vermiculite:CaCl2 mass ratio of 120:0.3. The resulting hydrogel was frozen at -18℃ for 2 hours, and then freeze-dried at -45℃ and 8Pa for 48 hours to obtain aerogel. Carbon nanotubes accounted for 17% of the total mass of the aerogel.
[0049] Example 4
[0050] (1) Preparation of vermiculite dispersion and sepiolite / carbon nanotube dispersion
[0051] 3.6 g of vermiculite was mixed with 100 mL of saturated NaCl solution and placed in a reaction vessel. The mixture was hydrothermally reacted at 110 °C for 2 h. After cooling, the mixture was filtered and washed with deionized water to remove the NaCl. Then, 100 mL of 2 mol / L LiCl solution was added, and the reaction was continued at 110 °C for another 2 h. After cooling, the mixture was centrifuged and washed 4-5 times with deionized water to remove LiCl. The washed expanded vermiculite was then added to deionized water and homogenized at 20,000 rpm for 15 min. The resulting vermiculite dispersion was centrifuged at 300 rpm for 60 min to remove impurities. The purified vermiculite dispersion was then concentrated by centrifuging at 7,000 rpm for 60 min to obtain a 30 mg / mL vermiculite dispersion.
[0052] 1g of sepiolite powder was mixed with 100mL of deionized water and dispersed for 30min using an ultrasonic cell disruptor to obtain a 10mg / mL sepiolite dispersion. Then, 1g of multi-walled carbon nanotube powder was added to 100mL of the 10mg / mL sepiolite dispersion and dispersed for 30min using an ultrasonic cell disruptor to obtain a 100mL sepiolite / carbon nanotube dispersion (mass ratio of sepiolite:carbon nanotube = 1, sepiolite dispersion concentration 10mg / mL).
[0053] (2) Preparation of vermiculite / sepiolite / carbon nanotube composite aerogel
[0054] Vermiculite dispersion was mixed with sepiolite / carbon nanotube dispersion at a mass ratio of vermiculite:sepiolite = 4. AlCl3 solution was added for crosslinking, with a vermiculite:CaCl2 mass ratio of 120:0.3. The resulting hydrogel was frozen at -18℃ for 2 hours, and then freeze-dried at -45℃ and 8Pa for 48 hours to obtain aerogel. Carbon nanotubes accounted for 17% of the total mass of the aerogel.
[0055] Example 5
[0056] (1) Preparation of vermiculite dispersion and sepiolite / carbon nanotube dispersion
[0057] 3.6 g of vermiculite was mixed with 100 mL of saturated NaCl solution and placed in a reaction vessel. The mixture was hydrothermally reacted at 110 °C for 2 h. After cooling, the mixture was filtered and washed with deionized water to remove the NaCl. Then, 100 mL of 2 mol / L LiCl solution was added, and the reaction was continued at 110 °C for another 2 h. After cooling, the mixture was centrifuged and washed 4-5 times with deionized water to remove LiCl. The washed expanded vermiculite was then added to deionized water and homogenized at 20,000 rpm for 15 min. The resulting vermiculite dispersion was centrifuged at 300 rpm for 60 min to remove impurities. The purified vermiculite dispersion was then concentrated by centrifuging at 7,000 rpm for 60 min to obtain a 30 mg / mL vermiculite dispersion.
[0058] 1g of sepiolite powder was mixed with 100mL of deionized water and dispersed for 30min using an ultrasonic cell disruptor to obtain a 10mg / mL sepiolite dispersion. Then, 1g of multi-walled carbon nanotube powder was added to 100mL of the 10mg / mL sepiolite dispersion and dispersed for 30min using an ultrasonic cell disruptor to obtain a 100mL sepiolite / carbon nanotube dispersion (mass ratio of sepiolite:carbon nanotube = 0.75, sepiolite dispersion concentration 10mg / mL).
[0059] (2) Preparation of vermiculite / sepiolite / carbon nanotube composite aerogel
[0060] Vermiculite dispersion was mixed with sepiolite / carbon nanotube dispersion at a mass ratio of vermiculite:sepiolite = 4. AlCl3 solution was added for crosslinking, with a vermiculite:AlCl3 mass ratio of 120:0.133. The resulting hydrogel was frozen at -18℃ for 2 hours, and then freeze-dried at -45℃ and 8Pa for 48 hours to obtain aerogel. Carbon nanotubes accounted for 21% of the total mass of the aerogel.
[0061] Example 6
[0062] (1) Preparation of vermiculite dispersion and sepiolite / carbon nanotube dispersion
[0063] 3.6 g of vermiculite was mixed with 100 mL of saturated NaCl solution and placed in a reaction vessel. The mixture was hydrothermally reacted at 110 °C for 2 h. After cooling, the mixture was filtered and washed with deionized water to remove the NaCl. Then, 100 mL of 2 mol / L LiCl solution was added, and the reaction was continued at 110 °C for another 2 h. After cooling, the mixture was centrifuged and washed 4-5 times with deionized water to remove LiCl. The washed expanded vermiculite was then added to deionized water and homogenized at 20,000 rpm for 15 min. The resulting vermiculite dispersion was centrifuged at 300 rpm for 60 min to remove impurities. The purified vermiculite dispersion was then concentrated by centrifuging at 7,000 rpm for 60 min to obtain a 30 mg / mL vermiculite dispersion.
[0064] 1g of sepiolite powder was mixed with 100mL of deionized water and dispersed for 30min using an ultrasonic cell disruptor to obtain a 10mg / mL sepiolite dispersion. Then, 1g of multi-walled carbon nanotube powder was added to 100mL of the 10mg / mL sepiolite dispersion and dispersed for 30min using an ultrasonic cell disruptor to obtain a 100mL sepiolite / carbon nanotube dispersion (mass ratio of sepiolite:carbon nanotube = 1:1, sepiolite dispersion concentration 10mg / mL).
[0065] (2) Preparation of vermiculite / sepiolite / carbon nanotube composite aerogel
[0066] Vermiculite dispersion was mixed with sepiolite / carbon nanotube dispersion at a mass ratio of vermiculite:sepiolite = 1. AlCl3 solution was added for crosslinking. The mass ratio of vermiculite to CaCl2 was 120:0.3, which prevented the formation of hydrogel.
[0067] Example 7
[0068] (1) Preparation of vermiculite dispersion and sepiolite / carbon black dispersion
[0069] 3.6 g of vermiculite was mixed with 100 mL of saturated NaCl solution and placed in a reaction vessel. The mixture was hydrothermally reacted at 110 °C for 2 h. After cooling, the mixture was filtered and washed with deionized water to remove the NaCl. Then, 100 mL of 2 mol / L LiCl solution was added, and the reaction was continued at 110 °C for another 2 h. After cooling, the mixture was centrifuged and washed 4-5 times with deionized water to remove LiCl. The washed expanded vermiculite was then added to deionized water and homogenized at 20,000 rpm for 15 min. The resulting vermiculite dispersion was centrifuged at 300 rpm for 60 min to remove impurities. The purified vermiculite dispersion was then concentrated by centrifuging at 7,000 rpm for 60 min to obtain a 30 mg / mL vermiculite dispersion.
[0070] Mix 1g of sepiolite powder with 100mL of deionized water and disperse using an ultrasonic cell disruptor for 30min to obtain a 10mg / mL sepiolite dispersion. Then add 1g of carbon black powder to 100mL of the 10mg / mL sepiolite dispersion and disperse using an ultrasonic cell disruptor for 30min to obtain a 100mL sepiolite / carbon black dispersion (mass ratio of sepiolite to carbon black = 1:1, sepiolite dispersion concentration 10mg / mL).
[0071] (2) Preparation of vermiculite / sepiolite / carbon black composite aerogel
[0072] Vermiculite dispersion was mixed with sepiolite / carbon black dispersion at a mass ratio of vermiculite:sepiolite = 4. AlCl3 solution was added for crosslinking, with a mass ratio of vermiculite to AlCl3 of 120:0.133. The resulting hydrogel was frozen at -18°C for 2 hours, and then freeze-dried at -45°C and 8 Pa for 48 hours to obtain aerogel. The carbon black accounted for 17% of the total mass of the aerogel.
[0073] Example 8
[0074] (1) Preparation of vermiculite dispersion and sepiolite / graphene dispersion
[0075] 3.6 g of vermiculite was mixed with 100 mL of saturated NaCl solution and placed in a reaction vessel. The mixture was hydrothermally reacted at 110 °C for 2 h. After cooling, the mixture was filtered and washed with deionized water to remove the NaCl. Then, 100 mL of 2 mol / L LiCl solution was added, and the reaction was continued at 110 °C for another 2 h. After cooling, the mixture was centrifuged and washed 4-5 times with deionized water to remove LiCl. The washed expanded vermiculite was then added to deionized water and homogenized at 20,000 rpm for 15 min. The resulting vermiculite dispersion was centrifuged at 300 rpm for 60 min to remove impurities. The purified vermiculite dispersion was then concentrated by centrifuging at 7,000 rpm for 60 min to obtain a 30 mg / mL vermiculite dispersion.
[0076] 1g of sepiolite powder was mixed with 100mL of deionized water and dispersed for 30min using an ultrasonic cell disruptor to obtain a 10mg / mL sepiolite dispersion. Then, 1g of graphene powder was added to 100mL of the 10mg / mL sepiolite dispersion and dispersed for 30min using an ultrasonic cell disruptor to obtain a 100mL sepiolite / graphene dispersion (mass ratio of sepiolite:graphene = 1:1, sepiolite dispersion concentration 10mg / mL).
[0077] (2) Preparation of vermiculite / sepiolite / graphene composite aerogel
[0078] Vermiculite dispersion was mixed with sepiolite / graphene dispersion at a mass ratio of vermiculite:sepiolite = 4. AlCl3 solution was added for crosslinking, with a mass ratio of vermiculite to AlCl3 of 120:0.133. The resulting hydrogel was frozen at -18°C for 2 hours, and then freeze-dried at -45°C and 8 Pa for 48 hours to obtain aerogel. The graphene content of the aerogel was 17% of the total mass.
[0079] Example 9
[0080] (1) Preparation of vermiculite dispersion and sepiolite / graphite dispersion
[0081] 3.6 g of vermiculite was mixed with 100 mL of saturated NaCl solution and placed in a reaction vessel. The mixture was hydrothermally reacted at 110 °C for 2 h. After cooling, the mixture was filtered and washed with deionized water to remove the NaCl. Then, 100 mL of 2 mol / L LiCl solution was added, and the reaction was continued at 110 °C for another 2 h. After cooling, the mixture was centrifuged and washed 4-5 times with deionized water to remove LiCl. The washed vermiculite was then added to deionized water and homogenized at 20,000 rpm for 15 min. The resulting vermiculite dispersion was centrifuged at 300 rpm for 60 min to remove impurities. The purified vermiculite dispersion was then concentrated by centrifuging at 7,000 rpm for 60 min to obtain a 30 mg / mL vermiculite dispersion.
[0082] 1g of sepiolite powder was mixed with 100mL of deionized water and dispersed for 30min using an ultrasonic cell disruptor to obtain a 10mg / mL sepiolite dispersion. Then, 1g of graphite powder was added to 100mL of the 10mg / mL sepiolite dispersion and dispersed for 30min using an ultrasonic cell disruptor to obtain a 100mL sepiolite / graphite dispersion (mass ratio of sepiolite:graphite = 1:1, sepiolite dispersion concentration 10mg / mL).
[0083] (2) Preparation of vermiculite / sepiolite / graphite composite aerogel
[0084] Vermiculite dispersion was mixed with sepiolite / graphite dispersion at a mass ratio of vermiculite:sepiolite = 4. AlCl3 solution was added for crosslinking, with a mass ratio of vermiculite to AlCl3 of 120:0.133. The resulting hydrogel was frozen at -18°C for 2 hours, and then freeze-dried at -45°C and 8 Pa for 48 hours to obtain aerogel. Graphite accounted for 17% of the total mass of the aerogel.
[0085] Performance tests were conducted on VSC-3, VSC-12, VSC-17, VSC-21, VSGT-17, VSGN-17, and VSCB-17. The results are as follows: Figure 1-5 The specific analysis is as follows:
[0086] SEM scans revealed that carbon nanotubes and sepiolite were intertwined, resulting in a uniform and stable sepiolite / carbon nanotube dispersion. VSC-17 exhibits a rich network of interconnected pores, facilitating rapid water transport. The addition of carbon nanotubes enhances solar energy absorption. Figure 1 ).
[0087] Analysis of the ultraviolet-visible-near-infrared absorption spectrum revealed that VSC-17 exhibited superior light absorption across the entire measurement range, with the added carbon nanotubes capable of absorbing the vast majority of visible light. Figure 2 ).
[0088] Pure water was obtained by irradiation with standard sunlight under a solar simulator. The evaporation rates of VSC-3, VSC-12, VSC-17, and VSC-21 were 0.39 kg m³, respectively. -2 h -1 2.11kg m -2 h -1 2.35kg m -2 h -1 2.53kg m -2 h -1 2.59 kgm -2 h -1 ( Figure 3 ).
[0089] Under standard sunlight irradiation using a solar simulator, the evaporation rates of VSGT-17, VSGN-17, and VSCB-17 were found to be 2.48 kg m³. -2 h -1 2.42kg m -2 h -1 2.57kg m -2 h -1 ( Figure 4 ).
[0090] By irradiating the dye wastewater from VSC-17 treatment with standard sunlight under a solar simulator, the condensate was collected and subjected to ultraviolet absorption spectroscopy analysis. The absorption peaks of methyl orange and methylene blue completely disappeared, indicating that the dyes were essentially 100% removed. Figure 5 ).
[0091] The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications and variations to the present invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention intends to include these modifications and variations.
Claims
1. A method for preparing a composite aerogel for a photothermal evaporator, characterized in that, Includes the following steps: (1) Preparation of sepiolite / nanocarbon dispersion Sepiolite powder was mixed with deionized water and dispersed using an ultrasonic cell disruptor. Then, nano-carbon material powder was added to the sepiolite dispersion and dispersed using an ultrasonic cell disruptor to obtain a sepiolite / nano-carbon dispersion. The mass ratio of sepiolite to nano-carbon was 0.75-7, and the concentration of sepiolite in the sepiolite / nano-carbon dispersion was 10 mg / mL. (2) Preparation of vermiculite dispersion Vermiculite was mixed with a saturated sodium chloride solution and placed in a reaction vessel. The mass ratio of vermiculite to saturated sodium chloride was controlled at 0.01-0.
03. The mixture was then subjected to a hydrothermal reaction at 105-125℃ for 1-3 h. After the mixture was washed by filtration with deionized water, 2 mol / L LiCl solution was added. The mass ratio of vermiculite to LiCl solution was controlled at 0.01-0.
03. The mixture was then subjected to a hydrothermal reaction at 105-125℃ for 1-3 h. Finally, the mixture was washed by filtration with deionized water to obtain expanded vermiculite. The expanded vermiculite was mixed with deionized water, and then subjected to peeling, centrifugation to remove impurities, and concentrated to a vermiculite dispersion of 6-40 mg / mL. (3) Preparation of composite aerogel Vermiculite dispersion was mixed with sepiolite / nanocarbon dispersion, with the mass ratio of vermiculite to sepiolite controlled at 3-4. AlCl3 solution was then added for cross-linking to obtain vermiculite / sepiolite / nanocarbon composite hydrogel. The vermiculite / sepiolite / nanocarbon composite hydrogel was frozen in a refrigerator for 2-3 h and then dried in a freeze dryer for 48 h to obtain vermiculite / sepiolite / nanocarbon composite aerogel. The mass ratio of vermiculite dispersion to 0.5 mol / L AlCl3 solution was 120:0.133-0.
350.
2. The preparation method according to claim 1, characterized in that, In step (2), the expanded vermiculite is mixed with deionized water and peeled off in a homogenizer at 20,000-22,000 rpm for 15-20 min. The resulting mixture is then placed in a centrifuge and centrifuged at 300 rpm for 60 min to remove impurities.
3. The preparation method according to claim 1, characterized in that, Nano-carbon accounts for 3-21% of the mass of vermiculite / sepiolite / nano-carbon composite hydrogels.
4. The preparation method according to claim 1, characterized in that, Nanocarbon includes multi-walled carbon nanotubes, carbon black, graphene, and graphite.
5. The application of the vermiculite / sepiolite / nanocarbon composite aerogel obtained by the preparation method according to any one of claims 1-4 in the treatment of seawater and dye wastewater.