Trapezoidal seawater evaporator with alternate three-dimensional hydrophilic and hydrophobic sponges

Abstract

The invention relates to an evaporator, in particular to a three-dimensional hydrophilic and hydrophobic sponge alternate trapezoidal seawater evaporator and a preparation method thereof. The invention provides a three-dimensional hydrophilic and hydrophobic sponge alternate trapezoidal seawater evaporator, which comprises three hydrophilic sponges and two hydrophobic sponges, the hydrophilic sponges and the hydrophobic sponges are alternately arranged in a trapezoidal shape, the top hydrophilic sponge forms a trapezoidal structure with height difference, the bottom hydrophobic sponge forms a groove structure, and the bottom hydrophobic sponge forms a trapezoidal structure with height difference. And two copper wires are connected and fixed in a penetrating mode through the connecting holes, and the three-dimensional trapezoid hydrophilic and hydrophobic spaced sponge evaporator is obtained. Through the design of the evaporator structure, sunlight on the upper surface of the evaporator is transmitted into the evaporator, so that a plurality of dark evaporation surfaces are formed in the evaporator, the actual evaporation area is increased, and the high evaporation efficiency is achieved under the limited illumination area.

Description

Technical Field

[0001] The present invention relates to an evaporator, and more particularly to a trapezoidal seawater evaporator with three-dimensional hydrophilic and hydrophobic sponges alternating and a preparation method thereof. Background Art

[0002] With the rapid development of society and the intensification of water pollution, coupled with factors such as drought and the increasing demand for domestic and industrial water, freshwater shortage has become a widespread global problem. Currently, various desalination technologies have been developed, such as electrodialysis, reverse osmosis, and distillation. However, these technologies require complex equipment and result in a large amount of energy consumption. On the other hand, solar evaporation has received extensive attention in recent years due to its green and environmentally friendly characteristics.

[0003] Most of the existing solar evaporators are limited by their inefficient structures, which restricts the achievement of high evaporation rates. By optimizing the structure of the evaporator and adjusting the balance between the evaporation amount and the water supply amount of the evaporator, the low efficiency problem of traditional evaporators can be solved. The transformation of solar evaporators from two-dimensional to three-dimensional structures not only increases the overall evaporation surface area under the same projected area but also expands the steam escape and energy input channels. Although these evaporators are optimized in structure and the evaporation efficiency is improved, the sunlight is not effectively utilized, resulting in the excess sunlight on the surface being dissipated in the air or bulk water. Summary of the Invention

[0004] In order to overcome the defects of the prior art, through the design of the evaporator structure, the present invention transmits the sunlight on the upper surface of the evaporator to the inside of the evaporator, so that multiple dark evaporation surfaces are formed inside the evaporator to increase the actual evaporation area, thereby achieving a higher evaporation efficiency under a limited illumination area.

[0005] On the one hand, the present invention provides a trapezoidal seawater evaporator with three-dimensional hydrophilic and hydrophobic sponges alternating, which includes three hydrophilic sponges and two hydrophobic sponges. The hydrophilic sponges and the hydrophobic sponges are arranged alternately and trapezoidally. The top hydrophilic sponge forms a trapezoidal structure with a height difference, and the bottom hydrophobic sponge forms a groove structure. Two copper wires are passed through the connecting holes for connection and fixation to obtain a three-dimensional trapezoidal hydrophilic-hydrophobic spacer sponge evaporator.

[0006] Among them, the hydrophilic sponge is modified with polyvinyl alcohol, tannic acid, and iron ions, showing good photothermal effects and superhydrophilicity; the hydrophobic sponge is modified with carbon nanotubes and polydimethylsiloxane, showing high thermal conductivity and superhydrophobic effects.

[0007] The present invention is formed by alternately arranging three hydrophilic and two hydrophobic sponges in a trapezoidal pattern and fixing them with two steel wires, forming a 3D trapezoidal evaporator. The hydrophilic part of the 3D evaporator provides a rapid water supply channel and evaporates at the top. The hydrophobic part, due to its high thermal conductivity and porous structure, can transfer heat to the interior of the evaporator, heating the hydrophilic part in contact with it, forming an evaporation layer between the two sponges, expanding the actual evaporation area, and thus increasing the evaporation rate. At the same time, due to the presence of the hydrophobic sponge, a rich steam escape channel can be provided.

[0008] Furthermore, the present invention provides a method for preparing the hydrophilic sponge, which includes the following steps:

[0009] 1) First, wash the sheet-shaped polyurethane sponge with distilled water and dry it for later use;

[0010] 2) Dissolve polyvinyl alcohol and ferric chloride hexahydrate in water and stir at 95 °C to obtain Solution 1;

[0011] 3) Dissolve tannic acid in water to obtain Solution 2;

[0012] 4) Immerse the washed sponge in Solution 1 and sonicate it, then dry it, then immerse it in Solution 2 and sonicate it, and then rinse it with distilled water

[0013] to obtain a superhydrophilic sponge.

[0014] Preferably, in step 2) of the method for preparing the hydrophilic sponge, the weight ratio of polyvinyl alcohol: ferric chloride hexahydrate: water is 3: 3.6: 97.

[0015] Preferably, in step 3) of the method for preparing the hydrophilic sponge, the weight ratio of tannic acid: water is 3: 97.

[0016] Furthermore, the present invention provides a method for preparing the hydrophobic sponge, which includes the following steps:

[0017] 1) First, wash the sheet-shaped polyurethane sponge with distilled water and dry it for later use;

[0018] 2) Using n-hexane as a solvent, add polydimethylsiloxane and a curing agent to n-hexane and stir to obtain Solution 3; add carbon nanotubes to Solution 3 and continue stirring, and then immerse the washed polyurethane sponge in the above solution;

[0019] 3) Dry the immersed sponge to obtain a superhydrophobic sponge.

[0020] Preferably, in step 2) of the method for preparing the hydrophobic sponge, the curing agent is Dow Corning SYLGARD 184, the weight ratio of polydimethylsiloxane to the curing agent is 10: 1, and the weight-to-volume ratio of carbon nanotubes: polydimethylsiloxane: n-hexane is 2 g: 2 g: 20 ml.

[0021] On the other hand, the present invention provides an application of the above-mentioned trapezoidal seawater evaporator with three-dimensional hydrophilic and hydrophobic sponges alternating in the field of seawater evaporation.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The present invention uses a sheet-shaped polyurethane sponge as the substrate, which is low-cost, easy to obtain, and has good scalability; the hydrophilic and hydrophobic sponges of the present invention are arranged at intervals, expanding the actual evaporation area; the bottom of the trapezoidal seawater evaporator with three-dimensional hydrophilic and hydrophobic sponges alternating in the present invention is a groove structure, improving the thermal management ability; the trapezoidal seawater evaporator with three-dimensional hydrophilic and hydrophobic sponges alternating in the present invention can operate stably for a long time in high-concentration brine, and the preparation materials used in the present invention are green and biodegradable. Description of the Drawings

[0024] Figure 1 It is a preparation flow chart of the trapezoidal seawater evaporator A with three-dimensional hydrophilic and hydrophobic sponges alternating in the present invention. Among them, (0) is a sheet-shaped polyurethane sponge, (1) is a hydrophilic sponge, (2) is a hydrophobic sponge, (3) is a trapezoidal structure, (4) is a groove structure, and (5) is a connecting hole.

[0025] Figure 2 It is a schematic plan view of the trapezoidal seawater evaporator A with three-dimensional hydrophilic and hydrophobic sponges alternating in the present invention. Among them, (1) is a hydrophilic sponge and (2) is a hydrophobic sponge.

[0026] Figure 3 It is the result of the thermal conductivity of the superhydrophobic sponge and the superhydrophilic sponge in the present invention.

[0027] Figure 4 It is a physical picture of the present invention and an infrared imaging picture during the evaporation process.

[0028] Figure 5 It is a schematic plan view of the comparative evaporators B, C, and D in the embodiment of the present invention. Among them, (1) is a hydrophilic sponge and (2) is a hydrophobic sponge.

[0029] Figure 6 It is a comparative graph of the evaporation rate changes of the present invention and the control group during continuous evaporation of 3.5% and 20% NaCl solutions for 8 hours.

[0030] Figure 7 It is an SEM picture of the original polyurethane sponge, the hydrophobic modified polyurethane sponge, and the hydrophilic modified polyurethane sponge.

[0031] Figure 8 It is a weight loss graph of the evaporation process of the present invention and the control group within one hour.

[0032] Figure 9This is the average evaporation rate graph of the continuous evaporation for 7 days of the present invention.

[0033] Figure 10 Before and after purifying natural seawater of the present invention, the + Na + , K 2+ , Mg 2+ , Ca ion concentration comparison graph before and after. Specific embodiments

[0034] The following further describes the present invention in detail with reference to the accompanying drawings and embodiments.

[0035] Embodiment 1 Preparation method of hydrophilic sponge

[0036] Clean the polyurethane sponge with distilled water and dry it for standby. Dissolve 3 g of polyvinyl alcohol and 3.6 g of ferric chloride hexahydrate in 97 g of water, and stir at 95 °C for 30 minutes to obtain Solution 1. Secondly, dissolve 3 g of tannic acid in 97 g of water to obtain Solution 2. Finally, immerse the cleaned sponge in Solution 1 and ultrasonicate for 2 hours, then dry it in an oven, and then immerse it in Solution 2 and ultrasonicate for 20 minutes, and then rinse it with distilled water 3 times to obtain a hydrophilic sponge.

[0037] Embodiment 2 Preparation method of hydrophobic sponge

[0038] Using n-hexane as a solvent, add 2 g of polydimethylsiloxane and the corresponding curing agent (Kangdaoning SYLGARD 184, mass ratio 10:1) to 20 ml of n-hexane solution and stir for 2 hours to obtain Solution 3. Add 2 g of carbon nanotubes to Solution 3 and continue to stir for 2 hours, and then immerse the cleaned polyurethane sponge in the above solution; place the immersed sponge in an oven and dry it for 12 hours to obtain a superhydrophobic sponge.

[0039] Embodiment 3 Trapezoidal seawater evaporator with three-dimensional hydrophilic and hydrophobic sponge phases

[0040] Arrange three hydrophilic sponges (1) and two hydrophobic sponges (2) alternately to form a trapezoidal structure (3) with a height difference at the top, and a groove structure (4) is formed at the bottom by the hydrophobic sponge. Fix them by threading two copper wires through the connection holes (5) to obtain an evaporator, named Evaporator A. The structure is shown in Figure 1 , 2 ; The physical diagram and infrared imaging diagram are shown in Figure 4 . As a control, using the hydrophilic sponge and hydrophobic sponge prepared above, evaporators B, C, and D were prepared by different structural arrangements. The structural arrangements of the evaporators are as shown in Figure 5 .

[0041] The hydrophilic and hydrophobic properties, thermal conductivity, and light absorption properties of the modified hydrophilic and hydrophobic sponges were tested, and SEM characterization and infrared testing were performed on their surfaces for analysis, as well as the water evaporation rate, recycling performance, durability, and salt tolerance of the three-dimensional trapezoidal hydrophilic-hydrophobic spacer sponge evaporator.

[0042] Infrared imaging: FLUKE TiS20 was used. + The infrared thermal imager recorded the real-time temperature changes of the samples. During the evaporation process, the temperature of the hydrophobic sponge was much higher than that of the hydrophilic sponge (dark color represents higher temperature), forming a cold evaporation surface on the side of the hydrophilic sponge.

[0043] SEM characterization: The surface morphology of the samples was characterized using a scanning electron microscope (SEM, Quanta fg-250, FEI, America).

[0044] Test of the average evaporation rate for 7 consecutive days of evaporation: Evaporation rate = weight of the evaporated water collected per day / (area of the evaporator * evaporation time). The solar simulator (pls-ske300, Beijing Perfectlight) simulated sunlight with a light intensity of 1 sun intensity.

[0045] Determination of the weight loss during the evaporation process within one hour: The beaker containing the salt solution and the floating evaporator were placed on a microelectronic balance (accuracy of 0.1 mg), and the mass change of the salt solution was recorded in real time. The weight loss value of the electronic balance was read every 5 minutes.

[0046] Test method for the evaporation rate of 3.5% and 20% NaCl solutions for 8 consecutive hours of evaporation: The beakers containing 3.5% and 20% NaCl solutions and the floating evaporators were respectively placed on a microelectronic balance (accuracy of 0.1 mg), and the mass loss after 8 hours of evaporation was recorded. Evaporation rate = mass loss after 8 hours / (8 hours * area of the evaporator).

[0047] Na in water before and after purifying natural seawater + , K + , Mg 2+ , Ca 2+ Ion concentration comparison test before and after: An inductively coupled plasma optical emission spectrometer (ICP-OES, Thermo, USA) was used to measure the metal ion concentrations of the samples before and after desalination of seawater in the East China Sea of Zhoushan City, Zhejiang Province.

[0048] Thermal conductivity of superhydrophobic and superhydrophilic sponges: In the present invention, a thermal constant analyzer (Hot Disk CTPS-2500S, Sweden) was used to test the thermal conductivity of the samples.

[0049] The results show that the thermal conductivity of the super hydrophobic sponge and super hydrophilic sponge prepared by the present invention is 0.071 W / (m·K) and 0.114 W / (m·K), respectively. Figure 3 The trapezoidal seawater evaporator with alternating three-dimensional hydrophilic and hydrophobic sponges prepared by the present invention can achieve 3.6 kg m -2 h -1 In the control group, the evaporation rates of evaporator B, evaporator C, and evaporator D in 3.5% NaCl solution were 2.76 kg m -2 h -1 , 2.93kg m -2 h -1 , 2.6kg m -2 h -1 , the evaporation rate is much lower than that of evaporator A, see Figure 6 In the 20% high concentration NaCl solution, evaporator A can also maintain 3.26 kg m -2 h -1 The evaporation rate of evaporator B and evaporator D dropped sharply after 2 hours of evaporation in a 20% high concentration NaCl solution. Figure 6 The evaporator A can also operate stably in acid, alkaline solution and organic solution. The SEM images of the super hydrophobic sponge, super hydrophilic sponge and original polyurethane sponge prepared by the present invention are shown in FIG. Figure 7 The present invention arranges the modified hydrophilic and hydrophobic sponges at intervals to form multiple cold evaporation surfaces inside the evaporator, thereby expanding the actual evaporation area. The trapezoidal arrangement at the top and the groove structure design at the bottom greatly improve the light-to-heat conversion performance and thermal management capability of the evaporator, thereby achieving a higher evaporation rate. The change in evaporation rate is shown in Figure 8 , and carried out 7 days of continuous evaporation test, the evaporation rate remained stable, see Figure 9 Take the East China Sea water for evaporation, and test the main ion concentrations in the water before and after evaporation. Figure 10 The ion concentration in the evaporated water is greatly reduced, meeting the drinking water standards of the World Health Organization.

[0050] Finally, it should be noted that the above examples are only some specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A trapezoidal seawater evaporator with three-dimensional hydrophilic and hydrophobic sponges alternating, characterized in that The trapezoidal seawater evaporator includes three hydrophilic sponges and two hydrophobic sponges. The hydrophilic sponges and hydrophobic sponges are arranged alternately and in a trapezoidal shape. The top hydrophilic sponge forms a trapezoidal structure with a height difference, and the bottom hydrophobic sponge forms a groove structure. Two copper wires are passed through the connection holes for threading and fixing to obtain a three-dimensional trapezoidal hydrophilic-hydrophobic spaced sponge evaporator.

2. The trapezoidal seawater evaporator with three-dimensional hydrophilic and hydrophobic sponges alternating as described in claim 1, characterized in that, The hydrophilic sponge is modified with polyvinyl alcohol, tannic acid, and iron ions, showing good photothermal effects and superhydrophilicity.

3. A trapezoidal seawater evaporator with a three-dimensional hydrophilic-hydrophobic sponge interphase as described in claim 1, characterized in that The hydrophobic sponge is modified with carbon nanotubes and polydimethylsiloxane, showing high thermal conductivity and superhydrophobic effects.

4. A trapezoidal seawater evaporator with three-dimensional hydrophilic and hydrophobic sponges alternating as described in claim 1, characterized in that, The preparation method of the hydrophilic sponge includes the following steps: 1) First, wash the sheet-shaped polyurethane sponge with distilled water and dry it for later use; 2) Dissolve polyvinyl alcohol and ferric chloride hexahydrate in water and stir at 95 °C to obtain Solution 1; 3) Dissolve tannic acid in water to obtain Solution 2; 4) Immerse the washed sponge in Solution 1 and sonicate it, then dry it. Then immerse it in Solution 2 and sonicate it again, and then wash it with distilled water to obtain a superhydrophilic sponge.

5. The trapezoidal seawater evaporator with a three-dimensional hydrophilic-hydrophobic sponge interphase according to claim 4, characterized in that, In step 2) of the preparation method of the hydrophilic sponge, the weight ratio of polyvinyl alcohol: ferric chloride hexahydrate: water is 3:3.6:

97.

6. The trapezoidal seawater evaporator with three-dimensional hydrophilic and hydrophobic sponges alternating as described in claim 4, characterized in that, In step 3) of the preparation method of the hydrophilic sponge, the weight ratio of tannic acid: water is 3:

97.

7. A trapezoidal seawater evaporator with a three-dimensional hydrophilic-hydrophobic sponge interphase as claimed in claim 1, wherein, The preparation method of the hydrophobic sponge includes the following steps: 1) First, wash the sheet-shaped polyurethane sponge with distilled water and dry it for later use; 2) Using n-hexane as a solvent, add polydimethylsiloxane and a curing agent to n-hexane and stir to obtain Solution 3; add carbon nanotubes to Solution 3 and continue stirring, and then immerse the washed polyurethane sponge in the above solution; 3) Dry the immersed sponge to obtain a superhydrophobic sponge.

8. A trapezoidal seawater evaporator with a three-dimensional hydrophilic-hydrophobic sponge interphase according to claim 7, characterized in that, In step 2) of the preparation method of the hydrophobic sponge, the curing agent is Dow Corning SYLGARD 184, and the weight ratio of polydimethylsiloxane to the curing agent is 10:

1.

9. The trapezoidal seawater evaporator with a three-dimensional hydrophilic-hydrophobic sponge interphase according to claim 7, wherein, In step 2) of the preparation method of the hydrophobic sponge, the weight / volume ratio of carbon nanotubes: polydimethylsiloxane: n-hexane is 2 g:2 g:20 ml.

10. The application of the three-dimensional trapezoidal seawater evaporator with hydrophilic-hydrophobic sponge intervals as described in claims 1-9 in the field of seawater evaporation.

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