A solar evaporation device
By using carbon aerogel with a micron-scale three-dimensional fibrous network structure coated on the surface of polyethylene foam in a solar evaporation device, the problem of salt deposition in the photothermal absorption layer in high-concentration brine was solved, achieving a highly efficient and stable evaporation effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TIANJIN UNIV
- Filing Date
- 2024-08-23
- Publication Date
- 2026-06-05
AI Technical Summary
Existing solar evaporation devices have poor operational stability in high-concentration brine, and salt deposition easily occurs in the photothermal absorption layer, affecting evaporation efficiency and device structure.
A carbon aerogel with a micron-scale three-dimensional fibrous network structure is used as a photothermal absorption layer, which prevents salt deposition and maintains long-term stable operation through buoyancy adjustment and salt ion retention design.
It achieves efficient evaporation in high-concentration brine, with no salt deposition in the photothermal absorption layer, and the device exhibits excellent stability and evaporation efficiency during continuous operation in high-concentration brine.
Smart Images
Figure CN118877993B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of solar evaporation technology, and more specifically to a solar evaporation device. Background Technology
[0002] The development of solar evaporation technology has simultaneously addressed the issues of limited fossil fuel reserves and freshwater scarcity. The core of this technology is converting solar energy into thermal energy to drive water evaporation. In traditional solar evaporation technologies, the photothermal absorption layer is located at the bottom of the water body, and the heat is dispersed throughout the water, reducing evaporation efficiency. With the introduction of the concept of solar interfacial evaporation, its high efficiency and zero energy consumption have attracted widespread attention. This technology concentrates heat on the surface of the evaporating water, avoiding heat loss to the water body, resulting in high evaporation efficiency. However, to maintain the long-term stable and efficient operation of a solar evaporation device, it is crucial that the photothermal absorption layer does not experience salt deposition. Salt deposition affects the light absorption of the photothermal absorption layer, reduces the evaporation efficiency, and may even further damage the structure of the evaporation device. Most existing devices are designed for short-term operation in freshwater or low-concentration saline solutions, exhibiting poor stability in high-concentration saline solutions. Summary of the Invention
[0003] The purpose of this invention is to provide a solar evaporation device that effectively solves the problem of salt deposition in the photothermal absorption layer, while having high evaporation efficiency and excellent operational stability in concentrated brine.
[0004] This invention provides a solar evaporation device, comprising polyethylene foam and carbon aerogel coated on the surface of the polyethylene foam;
[0005] The polyethylene foam is cylindrical or spherical.
[0006] Preferably, the thickness of the carbon aerogel covering the surface of the polyethylene foam is 1 to 3 mm.
[0007] Preferably, the carbon aerogel has a micron-scale three-dimensional fibrous network structure.
[0008] Preferably, the method for preparing the carbon aerogel includes the following steps:
[0009] Corrugated paper was degraded in a non-neutral solution and then dried to obtain lignocellulose.
[0010] The lignocellulose and solvent are mixed, and the resulting mixture is then subjected to freezing, freeze-drying, and carbonization in sequence to obtain the carbon aerogel.
[0011] Preferably, the non-neutral solution is an acid or an alkaline solution;
[0012] The acid solution includes one or more of phosphoric acid, hydrochloric acid, and sulfuric acid;
[0013] The alkaline solution includes potassium hydroxide solution and / or sodium hydroxide solution.
[0014] Preferably, the mass percentage concentration of the acid solution is 0.5-10%;
[0015] The mass percentage concentration of the alkaline solution is 1-15%.
[0016] Preferably, the solvent includes water or an aqueous solution of polyvinyl alcohol;
[0017] The polyvinyl alcohol in the aqueous solution has a mass percentage concentration of 0.05% to 5%.
[0018] Preferably, the mass percentage concentration of lignocellulose fibers in the mixture is 1-5%.
[0019] Preferably, the freezing temperature is -10 to -50°C, and the freezing time is 10 to 24 hours;
[0020] The freeze-drying time is 24–48 hours.
[0021] Preferably, the carbonization temperature is 800℃, the holding time is 4-8h, and the heating rate is 5-10℃ / min.
[0022] This invention provides a solar evaporation device comprising polyethylene foam (PE) and a carbon aerogel coating the surface of the PE foam; the PE foam is cylindrical or spherical. The PE foam of this invention has a low density, resulting in buoyancy greater than gravity, allowing the entire evaporation device to float on water. Incident sunlight is absorbed by the photothermal absorption layer (carbon aerogel) and converted into heat energy; the low thermal conductivity of PE prevents heat from being transferred downwards to the water. Under capillary action, seawater is transported to the top of the photothermal absorption layer, where it is heated and evaporates into water vapor. Impurities such as salt ions in the water are retained in the photothermal absorption layer, and the accumulation of salt ions affects the light absorption of the layer. By defining the shape of the solar evaporation device, the buoyancy it experiences in the initial stage of evaporation is greater than gravity (e.g., ...). Figure 1 As shown in Figure i), as evaporation proceeds, the salt accumulated on the surface of the evaporator gradually increases, and at this point, the gravity of the evaporation device gradually approaches buoyancy (as shown in Figure i). Figure 1 As shown in ii), the device will gradually tilt under the influence of gravity. As the evaporation process continues, the weight of the evaporation device becomes greater than the buoyancy, causing the evaporation device to tilt. The salt accumulated on the top of the photothermal absorption layer of the evaporation device is dissolved by seawater (e.g., as shown in ii). Figure 1(As shown in iii). At this time, the new photothermal absorption layer of the evaporator will be re-exposed to sunlight to continue the evaporation process, realizing a salt-resistant evaporator that can operate stably in seawater for a long time (such as...). Figure 1 (As shown). Attached Figure Description
[0023] Figure 1 This is a schematic diagram illustrating the working principle of the solar evaporation device described in this invention;
[0024] Figure 2 The image shows a SEM image of the carbon aerogel described in Example 1.
[0025] Figure 3 Water contact angle test of the carbon aerogel described in Example 1;
[0026] Figure 4 The curve showing the effect of wavelength on the light absorption rate of the carbon aerogel described in Example 1;
[0027] Figure 5 The evaporation performance of the solar evaporation device described in Example 1. Detailed Implementation
[0028] This invention provides a solar evaporation device, comprising polyethylene foam and carbon aerogel coated on the surface of the polyethylene foam;
[0029] The polyethylene foam is cylindrical or spherical.
[0030] In this invention, the thickness of the carbon aerogel covering the surface of the polyethylene foam is preferably 1 to 3 mm, more preferably 1.5 to 2.5 mm, and most preferably 1.8 to 2.2 mm.
[0031] In this invention, the porous structure of the carbon aerogel is preferably a micron-scale three-dimensional fibrous network structure. This micron-scale three-dimensional fibrous network structure enhances water transport and water vapor transmission; the carbon aerogel has a strong water absorption capacity, ensuring a sufficient water source during evaporation; and the carbon aerogel has a weighted average absorptivity of approximately 98% in the solar band, exhibiting excellent photothermal conversion capabilities.
[0032] In this invention, the method for preparing the carbon aerogel preferably includes the following steps:
[0033] Corrugated paper was degraded in a non-neutral solution and then dried to obtain lignocellulose.
[0034] The lignocellulose and solvent are mixed, and the resulting mixture is then subjected to freezing, freeze-drying, and carbonization in sequence to obtain the carbon aerogel.
[0035] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.
[0036] This invention degrades corrugated paper in a non-neutral solution and dries it to obtain lignocellulose.
[0037] Before the degradation process, the corrugated paper is preferably pretreated, which preferably includes sequential crushing, soaking, and washing. In this invention, the corrugated paper is preferably waste corrugated paper. In this invention, the soaking is preferably carried out in deionized water; the washing is preferably carried out under ultrasonic conditions. This invention does not impose any special limitations on the crushing, soaking, and ultrasonic processes; processes well-known to those skilled in the art can be used.
[0038] In this invention, the non-neutral solution is preferably an acid or an alkali solution; the acid preferably includes one or more of phosphoric acid, hydrochloric acid, and sulfuric acid. When the acid is two or more of the above-mentioned specific choices, this invention does not have any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio; the alkali solution preferably includes potassium hydroxide solution and / or sodium hydroxide solution. When the alkali solution is potassium hydroxide solution and sodium hydroxide solution, this invention does not have any special limitation on the ratio of potassium hydroxide solution and sodium hydroxide solution, and they can be mixed in any ratio. In this invention, the mass percentage concentration of the acid solution is preferably 0.5-10%, more preferably 2-8%, and most preferably 4-6%; the mass percentage concentration of the alkali solution is preferably 1-15%, more preferably 3-12%, and most preferably 5-9%.
[0039] In this invention, the degradation is preferably carried out under stirring conditions, wherein the stirring temperature is preferably 20-40°C; the stirring speed is preferably 200-400 rpm, more preferably 250-350 rpm; and the stirring time is preferably 5-10 h, more preferably 6-8 h.
[0040] After the degradation is completed, the present invention preferably includes cleaning, and the cleaning is preferably performed using deionized water. The present invention does not impose any special limitations on the cleaning process, and any process known to those skilled in the art can be used.
[0041] In this invention, the drying temperature is preferably 50–70°C, more preferably 50–60°C, and most preferably 60°C; the drying time is preferably 1–3 hours, more preferably 2–3 hours, and most preferably 2 hours. In this invention, the drying is preferably carried out in a forced-air drying oven.
[0042] After obtaining lignocellulose, the present invention mixes the lignocellulose with a solvent, and then freezes, freeze-dries and carbonizes the resulting mixture in sequence to obtain the carbon aerogel.
[0043] In this invention, the solvent preferably includes water or an aqueous solution of polyvinyl alcohol (PVA); the mass percentage concentration of PVA in the aqueous PVA solution is preferably 0.05–5%, more preferably 1–4%, and most preferably 2–3%. In this invention, the preparation of the aqueous PVA solution preferably includes dissolving PVA in deionized water; the dissolution temperature is preferably 80–90°C, more preferably 85–90°C, and most preferably 90°C; the dissolution time is preferably 1–3 hours, more preferably 2–3 hours, and most preferably 2 hours. In this invention, the dissolution is preferably carried out in a rotating water bath.
[0044] The present invention does not impose any special limitations on the mixing process; any process known to those skilled in the art can be used.
[0045] In this invention, the mass percentage concentration of lignocellulose fibers in the mixture is preferably 1-5%, more preferably 1-4%, and most preferably 2-3%.
[0046] In this invention, the freezing temperature is preferably -10 to -50°C, more preferably -20 to -30°C, and most preferably -25 to -30°C; the freezing time is preferably 10 to 24 hours, more preferably 12 to 15 hours, and most preferably 15 hours; the freeze-drying time is preferably 24 to 48 hours, more preferably 30 to 36 hours, and most preferably 36 hours.
[0047] In this invention, the carbonization temperature is preferably 700-900℃, more preferably 700-800℃, and most preferably 800℃; the holding time is preferably 4-8h, more preferably 5-6h, and most preferably 6h; the heating rate is preferably 5-10℃ / min, more preferably 5-7℃ / min, and most preferably 5℃ / min.
[0048] In this invention, the method for preparing the solar evaporation device preferably includes the following steps:
[0049] The solar evaporation device is obtained by coating the surface of polyethylene foam with carbon aerogel.
[0050] The present invention does not impose any special limitations on the coating process, and any process known to those skilled in the art can be used.
[0051] The solar evaporation device provided by the present invention will be described in detail below with reference to the embodiments, but these should not be construed as limiting the scope of protection of the present invention.
[0052] Example 1
[0053] Shred the waste corrugated cardboard (the shredded paper should be 1×1cm in size). 2After soaking in deionized water and ultrasonic cleaning, the lignocellulose was stirred in a 5 wt% phosphoric acid solution (200 rpm) for 8 hours to complete the degradation of lignocellulose. After washing with deionized water, it was dried in a 60°C forced-air drying oven for 2 hours to obtain lignocellulose.
[0054] Add 0.6g of polyvinyl alcohol to 19.4g of deionized water and dissolve it in a rotating water bath at 90℃ to obtain a polyvinyl alcohol aqueous solution with a mass concentration of 3wt%.
[0055] After mixing 0.7g of lignocellulose and 20g of the polyvinyl alcohol aqueous solution, the mixture was successively frozen (at -30℃ for 15h) and freeze-dried (for 36h). The mixture was then placed in a tube furnace and heated to 800℃ in a nitrogen atmosphere at a heating rate of 5℃ / min and held for 6h to obtain carbon aerogel.
[0056] The carbon aerogel is coated onto the surface of polyethylene foam (with a radius of 1.5 cm and a height of 4 cm) to obtain the solar evaporation device (the thickness of the carbon aerogel layer is 1 mm).
[0057] The carbon aerogel was subjected to SEM testing, and the test results are as follows: Figure 2 As shown, by Figure 2 It is known that the microstructure of carbon aerogels possesses a distinct fibrous network, which is crucial for water transport during interfacial evaporation. These interwoven fibers form a three-dimensional network, providing numerous micron-sized pores that facilitate water transport and water vapor transport. Furthermore, the three-dimensional porous structure provides more surface area for light absorption during evaporation, thus enhancing evaporation performance.
[0058] The carbon aerogel was tested for water contact angle using a water contact angle tester. The test results are as follows: Figure 3 As shown, by Figure 3 It can be seen that water droplets can be completely absorbed by carbon aerogel in a very short time (~0.05s), which shows that carbon aerogel has a very strong water transport capacity and can ensure that sufficient water is provided during the evaporation process.
[0059] The effect of wavelength on the absorbance of the carbon aerogel was tested using a UV-VIS-NIR spectrophotometer. The test results are as follows: Figure 4 As shown, by Figure 4 It can be seen that carbon aerogel has a strong absorption capacity for solar wavelengths (weighted average absorption rate ~98%).
[0060] The solar evaporation device was subjected to evaporation performance testing. The testing process involved providing solar energy input to a solar simulator (AM 1.5), and using a computer and electronic balance (accuracy 0.0001g, counting frequency 2s) to record mass data in real time to monitor changes in the simulated seawater mass. Before the experiment, the simulator's irradiance was calibrated using a solar power meter to ensure that the radiation intensity irradiating the carbon aerogel surface was 1 kWm. -2 To ensure the accuracy of the experiment, the laboratory temperature and humidity were kept stable at approximately 24℃ and 65%, respectively.
[0061] Test results are as follows Figure 5 As shown, by Figure 5 It can be seen that the measured evaporation rate of the solar evaporation device under standard solar irradiation is 1.43 kg·m³. -2 ·h -1 The evaporation efficiency is 97.3%. The solar evaporation device can operate continuously for more than 6 hours in a sodium chloride solution with a mass concentration of 15 wt%, and no salt deposition occurs in the photothermal absorption layer (carbon aerogel).
[0062] Example 2
[0063] Shred the waste corrugated cardboard (the shredded paper should be 1×1cm in size). 2 After soaking in deionized water and ultrasonic cleaning, the lignocellulose was stirred in a 0.5% phosphoric acid solution (200 rpm) for 8 hours to complete the degradation of lignocellulose. After washing with deionized water, it was dried in a forced-air drying oven at 60°C for 2 hours to obtain lignocellulose.
[0064] Add 0.6g of polyvinyl alcohol to 19.4g of deionized water and dissolve it in a rotating water bath at 90℃ to obtain a 3% (w / w) polyvinyl alcohol aqueous solution.
[0065] After mixing 0.7g of lignocellulose and 20g of the polyvinyl alcohol aqueous solution, the mixture was successively frozen (at -30℃ for 15h) and freeze-dried (for 36h). The mixture was then placed in a tube furnace and heated to 800℃ in a nitrogen atmosphere at a heating rate of 5℃ / min and held for 6h to obtain carbon aerogel.
[0066] The carbon aerogel is coated onto the surface of polyethylene foam (with a radius of 1.5 cm and a height of 4 cm) to obtain the solar evaporation device (the thickness of the carbon aerogel layer is 1 mm).
[0067] The solar evaporation device was subjected to evaporation performance testing. The testing process involved providing solar energy input to a solar simulator (AM 1.5), and using a computer and electronic balance (accuracy 0.0001g, counting frequency 2s) to record mass data in real time to monitor changes in the simulated seawater mass. Before the experiment, the simulator's irradiance was calibrated using a solar power meter to ensure that the radiation intensity irradiating the carbon aerogel surface was 1 kWm. -2 To ensure the accuracy of the experiment, the laboratory temperature and humidity were stabilized at approximately 24℃ and 65%, respectively. The measured evaporation rate of the solar evaporation device under standard solar irradiation was 1.12 kg·m³. -2 ·h -1 The evaporation rate is 76.2%, and the solar evaporation device can operate continuously for more than 6 hours in a sodium chloride solution with a mass concentration of 15 wt%, and no salt deposition occurs in the photothermal absorption layer (carbon aerogel).
[0068] Example 3
[0069] Shred the waste corrugated cardboard (the shredded paper should be 1×1cm in size). 2 After soaking in deionized water and ultrasonic cleaning, the lignocellulose was stirred in a 5% phosphoric acid solution (200 rpm) for 8 hours to complete the degradation of lignocellulose. After washing with deionized water, it was dried in a 60°C forced-air drying oven for 2 hours to obtain lignocellulose.
[0070] Add 0.6g of polyvinyl alcohol to 19.4g of deionized water and dissolve it in a rotating water bath at 90℃ to obtain a 3% (w / w) polyvinyl alcohol aqueous solution.
[0071] After mixing 0.7g of lignocellulose and 20g of the polyvinyl alcohol aqueous solution, the mixture was successively frozen (at -30℃ for 15h) and freeze-dried (for 36h). The mixture was then placed in a tube furnace and heated to 800℃ in a nitrogen atmosphere at a heating rate of 5℃ / min and held for 6h to obtain carbon aerogel.
[0072] The carbon aerogel is coated onto the surface of polyethylene foam (with a radius of 1.5 cm and a height of 4 cm) to obtain the solar evaporation device (the thickness of the carbon aerogel layer is 3 mm).
[0073] The solar evaporation device was subjected to evaporation performance testing. The testing process involved providing solar energy input to a solar simulator (AM 1.5), and using a computer and electronic balance (accuracy 0.0001g, counting frequency 2s) to record mass data in real time to monitor changes in the simulated seawater mass. Before the experiment, the simulator's irradiance was calibrated using a solar power meter to ensure that the radiation intensity irradiating the carbon aerogel surface was 1 kWm. -2To ensure the accuracy of the experiment, the laboratory temperature and humidity were stabilized at approximately 24℃ and 65%, respectively. The measured evaporation rate of the solar evaporation device under standard solar irradiation was 0.72 kg·m³. -2 ·h -1 The evaporation rate is 48.9%, and the solar evaporation device can operate continuously for more than 6 hours in a sodium chloride solution with a mass concentration of 15 wt%, and no salt deposition occurs in the photothermal absorption layer (carbon aerogel).
[0074] Example 4
[0075] Shred the waste corrugated cardboard (the shredded paper should be 1×1cm in size). 2 After soaking in deionized water and ultrasonic cleaning, the lignocellulose was stirred in a 0.5% phosphoric acid solution (200 rpm) for 8 hours to complete the degradation of lignocellulose. After washing with deionized water, it was dried in a forced-air drying oven at 60°C for 2 hours to obtain lignocellulose.
[0076] Add 0.01g of polyvinyl alcohol to 19.99g of deionized water and dissolve it in a rotating water bath at 90℃ to obtain a polyvinyl alcohol aqueous solution with a mass concentration of 0.05%.
[0077] After mixing 0.7g of lignocellulose and 20g of the polyvinyl alcohol aqueous solution, the mixture was successively frozen (at -30℃ for 15h) and freeze-dried (for 36h). The mixture was then placed in a tube furnace and heated to 800℃ in a nitrogen atmosphere at a heating rate of 5℃ / min and held for 6h to obtain carbon aerogel.
[0078] The carbon aerogel is coated onto the surface of polyethylene foam (with a radius of 1.5 cm and a height of 4 cm) to obtain the solar evaporation device (the thickness of the carbon aerogel layer is 1 mm).
[0079] The solar evaporation device was subjected to evaporation performance testing. The testing process involved providing solar energy input to a solar simulator (AM 1.5), and using a computer and electronic balance (accuracy 0.0001g, counting frequency 2s) to record mass data in real time to monitor changes in the simulated seawater mass. Before the experiment, the simulator's irradiance was calibrated using a solar power meter to ensure that the radiation intensity irradiating the carbon aerogel surface was 1 kWm. -2 To ensure the accuracy of the experiment, the laboratory temperature and humidity were stabilized at approximately 24℃ and 65%, respectively. The measured evaporation rate of the solar evaporation device under standard solar irradiation was 0.98 kg·m³. -2 ·h -1The evaporation rate is 66.7%, and the solar evaporation device can operate continuously for more than 6 hours in a sodium chloride solution with a mass concentration of 15 wt%, and no salt deposition occurs in the photothermal absorption layer (carbon aerogel).
[0080] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A solar evaporation device, characterized in that, Includes polyethylene foam and carbon aerogel covering the surface of the polyethylene foam; The polyethylene foam is cylindrical, with a radius of 1.5 cm and a height of 4 cm; The carbon aerogel has a micron-scale three-dimensional fibrous network structure. The preparation method of the carbon aerogel is as follows: Waste corrugated paper was pulverized, soaked in deionized water, and ultrasonically cleaned. Then, it was stirred in a 5wt% phosphoric acid solution at 200 rpm for 8 hours to complete the degradation of lignocellulose. After washing with deionized water, it was dried in a 60℃ forced-air drying oven for 2 hours to obtain lignocellulose. The pulverized waste corrugated paper had a size of 1×1 cm. 2 ; Add 0.6g of polyvinyl alcohol to 19.4g of deionized water and dissolve it in a rotating water bath at 90℃ to obtain a polyvinyl alcohol aqueous solution with a mass concentration of 3wt%. After mixing 0.7g of lignocellulose and 20g of the polyvinyl alcohol aqueous solution, the mixture was freeze-dried and freeze-dried for 36h in sequence. Then, it was placed in a tube furnace and heated to 800℃ in a nitrogen atmosphere at a heating rate of 5℃ / min and held for 6h to obtain carbon aerogel. The freezing temperature was -30℃ and the time was 15h. The thickness of the carbon aerogel covering the surface of the polyethylene foam is 1 mm.