A trapezoidal seawater evaporator with three-dimensional hydrophilic and hydrophobic sponge phases

Abstract

This invention relates to evaporators, specifically to a three-dimensional trapezoidal seawater evaporator with alternating hydrophilic and hydrophobic sponges and its preparation method. The invention provides a three-dimensional trapezoidal seawater evaporator with alternating hydrophilic and hydrophobic sponges, comprising three hydrophilic sponges and two hydrophobic sponges arranged alternately in a trapezoidal pattern. The top hydrophilic sponge forms a trapezoidal structure with a height difference, while the bottom hydrophobic sponge forms a grooved structure. Two copper wires are used to connect and fix the evaporator through connecting holes, resulting in a three-dimensional trapezoidal hydrophilic and hydrophobic spaced sponge evaporator. This invention, through the design of the evaporator structure, transmits sunlight from the upper surface of the evaporator to the interior, creating multiple dark evaporation surfaces inside the evaporator to increase the actual evaporation area, thereby achieving high evaporation efficiency with a limited light-illuminated area.

Description

Technical Field

[0001] This invention relates to evaporators, specifically to a three-dimensional trapezoidal seawater evaporator with alternating hydrophilic and hydrophobic sponge phases and its preparation method. Background Technology

[0002] With rapid societal development and increasing water pollution, coupled with factors such as drought and rising demand for domestic and industrial water, freshwater scarcity has become a widespread global problem. Various desalination technologies have been developed, such as electrodialysis, reverse osmosis, and distillation; however, these technologies require complex equipment and result in significant energy consumption. On the other hand, solar evaporation has received widespread attention in recent years due to its green and environmentally friendly characteristics.

[0003] Most existing solar evaporators are limited by their inefficient structure, which restricts the achievement of high evaporation rates. The inefficiency of traditional evaporators can be addressed by optimizing their structure and adjusting the balance between evaporation rate and water supply. The shift from a two-dimensional to a three-dimensional structure in solar evaporators not only increases the overall evaporation surface area for the same projected area but also expands the channels for steam escape and energy input. While these evaporators are structurally optimized and improve evaporation efficiency, they do not effectively utilize sunlight, resulting in excess sunlight being lost into the air or bulk water. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention designs the evaporator structure to transmit sunlight from the upper surface of the evaporator into the interior of the evaporator, creating multiple dark evaporation surfaces inside the evaporator to increase the actual evaporation area, thereby achieving higher evaporation efficiency under limited illumination area.

[0005] On one hand, the present invention provides a three-dimensional trapezoidal seawater evaporator with alternating hydrophilic and hydrophobic sponges, which includes three hydrophilic sponges and two hydrophobic sponges. The hydrophilic and hydrophobic sponges alternate and are arranged 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 used to connect and fix the sponges through connecting holes to obtain a three-dimensional trapezoidal hydrophilic and hydrophobic alternating sponge evaporator.

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

[0007] This invention constructs a 3D trapezoidal evaporator by alternating three hydrophilic and two hydrophobic sponges arranged in a trapezoidal pattern and secured with two steel wires. The hydrophilic portion of the 3D evaporator provides a rapid water supply channel and evaporates at the top. The hydrophobic portion, due to its high thermal conductivity and porous structure, transfers heat to the interior of the evaporator, heating the hydrophilic portion in contact with it. This creates an evaporation layer between the two sponges, expanding the actual evaporation area and thus increasing the evaporation rate. Simultaneously, the presence of the hydrophobic sponges provides ample steam escape channels.

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

[0009] 1) First, wash the sheet 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) Soak the cleaned sponge in solution 1 and sonicate, then dry it, soak it in solution 2 and sonicate again, then rinse with distilled water.

[0013] Washing yields a superhydrophilic sponge.

[0014] Preferably, 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.

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

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

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

[0018] 2) Using hexane as a solvent, polydimethylsiloxane and curing agent were added to hexane and stirred to obtain solution 3; carbon nanotubes were added to solution 3 and stirring was continued, and then the cleaned polyurethane sponge was soaked in the above solution;

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

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

[0021] Furthermore, this invention provides the application of the aforementioned three-dimensional trapezoidal seawater evaporator with alternating hydrophilic and hydrophobic sponge phases in the field of seawater evaporation.

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

[0023] This invention uses sheet-like polyurethane sponge as a base, which is low-cost, readily available, and highly scalable. The alternating arrangement of hydrophilic and hydrophobic sponges in this invention expands the actual evaporation area. The bottom of the trapezoidal seawater evaporator with alternating three-dimensional hydrophilic and hydrophobic sponges has a groove structure, which improves thermal management capabilities. The trapezoidal seawater evaporator with alternating three-dimensional hydrophilic and hydrophobic sponges in this invention can operate stably in high-concentration brine for a long time. The preparation materials used in this invention are green and biodegradable. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the preparation process of the three-dimensional trapezoidal seawater evaporator A with alternating hydrophilic and hydrophobic sponges according to the present invention. In the diagram, (0) is a sheet-like polyurethane sponge, (1) is a hydrophilic sponge, (2) is a hydrophobic sponge, (3) is a trapezoidal structure, (4) is a grooved structure, and (5) is a connecting hole.

[0025] Figure 2 This is a schematic diagram of the planar structure of the trapezoidal seawater evaporator A with alternating hydrophilic and hydrophobic sponges of the present invention. Among them, (1) is a hydrophilic sponge and (2) is a hydrophobic sponge.

[0026] Figure 3 The results show the thermal conductivity of the superhydrophobic and superhydrophilic sponges of this invention.

[0027] Figure 4 These are physical images of the present invention and infrared images of the evaporation process.

[0028] Figure 5 This is a schematic diagram of the planar structure of evaporator B, evaporator C, and evaporator D in an embodiment of the present invention. Among them, (1) is a hydrophilic sponge, and (2) is a hydrophobic sponge.

[0029] Figure 6 This is a comparison graph showing the changes in evaporation rate between the present invention and the control group after continuous evaporation in 3.5% and 20% NaCl solutions for 8 hours.

[0030] Figure 7 SEM images of the original polyurethane foam, hydrophobically modified polyurethane foam, and hydrophilic modified polyurethane foam.

[0031] Figure 8 This is a graph showing the weight loss during the evaporation process of the present invention and the control group over one hour.

[0032] Figure 9This is a graph showing the average evaporation rate over 7 consecutive days of evaporation according to the present invention.

[0033] Figure 10 This invention relates to the purification of natural seawater before and after the removal of Na+. + K + Mg 2+ Ca 2+ Comparison of ion concentrations before and after. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0035] Example 1: Preparation method of hydrophilic sponge

[0036] The polyurethane sponge was washed with distilled water and dried for later use. 3g of polyvinyl alcohol and 3.6g of ferric chloride hexahydrate were dissolved in 97g of water and stirred at 95℃ for 30 minutes to obtain solution 1. Next, 3g of tannic acid was dissolved in 97g of water to obtain solution 2. Finally, the washed sponge was soaked in solution 1 and sonicated for 2 hours, then dried in a drying oven, and then soaked in solution 2 and sonicated for 20 minutes. Finally, it was rinsed three times with distilled water to obtain a hydrophilic sponge.

[0037] Example 2: Preparation method of hydrophobic sponge

[0038] Using hexane as a solvent, 2g of polydimethylsiloxane and the corresponding curing agent (SYLGARD 184, mass ratio 10:1) were added to 20ml of hexane solution and stirred for 2 hours to obtain solution 3. 2g of carbon nanotubes were added to solution 3 and stirred for another 2 hours. The cleaned polyurethane sponge was then soaked in the above solution. The soaked sponge was placed in a drying oven and dried for 12 hours to obtain a superhydrophobic sponge.

[0039] Example 3: Three-dimensional trapezoidal seawater evaporator with alternating hydrophilic and hydrophobic sponge phases

[0040] Three hydrophilic sponges (1) and two hydrophobic sponges (2) are arranged alternately to form a trapezoidal structure (3) with a height difference at the top and a groove structure (4) formed by the hydrophobic sponge at the bottom. Two copper wires are threaded through the connecting hole (5) to fix the evaporator, which is named Evaporator A. The structure is shown in the figure. Figure 1 , 2 The actual object image and infrared image can be found here. Figure 4 As a control, evaporators B, C, and D were prepared using the hydrophilic and hydrophobic sponges described above, with different structural arrangements, as shown in the figure. Figure 5 As shown.

[0041] The modified hydrophilic and hydrophobic sponges were tested for their hydrophilic and hydrophobic properties, thermal conductivity, and light absorption properties. Their surfaces were characterized by SEM and infrared spectroscopy. The water evaporation rate, recycling performance, durability, and salt resistance of the three-dimensional trapezoidal hydrophilic and hydrophobic spacer sponge evaporator were also analyzed.

[0042] Infrared imaging: using FLUKE TiS20 + Infrared thermal imagers record the real-time temperature changes of the sample. During the evaporation process, the temperature of the hydrophobic sponge is much higher than that of the hydrophilic sponge (the darker color indicates a 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 scanning electron microscopy (SEM, Quanta fg-250, FEI, America).

[0044] Test of average evaporation rate over 7 consecutive days: Evaporation rate = weight of evaporated water collected daily / (area of ​​evaporator * evaporation time). A solar simulator (pls-ske300, Beijing Perfectlight) simulates sunlight with a light intensity of 1 solar intensity.

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

[0046] Evaporation rate test method for 3.5% and 20% NaCl solutions continuously evaporated for 8 hours: Place beakers and floating evaporators containing 3.5% and 20% NaCl solutions respectively on a microelectronic balance (accuracy of 0.1 mg), record the mass loss after 8 hours of evaporation, and calculate the evaporation rate as: mass loss after 8 hours / (8 hours * evaporator area).

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

[0048] Thermal conductivity of superhydrophobic and superhydrophilic sponges: The thermal conductivity of the samples was tested using a thermal constant analyzer (CTPS-2500S, Sweden).

[0049] The results show that the thermal conductivity of the superhydrophobic sponge and superhydrophilic sponge prepared in this invention are 0.071 W / (m·K) and 0.114 W / (m·K), respectively. Figure 3 The three-dimensional trapezoidal seawater evaporator with alternating hydrophilic and hydrophobic sponge phases prepared in this invention achieved a flow rate of 3.6 kg m³ in a 3.5% NaCl solution. -2 h -1 The high evaporation rate of evaporator B, evaporator C, and evaporator D in 3.5% NaCl solution was observed in the control group, while their evaporation rates were 2.76 kg / m³. -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 Evaporator A can maintain a flow rate of 3.26 kg m³ even in a 20% high-concentration NaCl solution. -2 h -1 The higher evaporation rate of evaporator B allows it to maintain a stable evaporation rate for 8 hours of continuous evaporation. However, in evaporators B and D, the evaporation rate drops sharply after 2 hours of evaporation in a 20% high-concentration NaCl solution. Figure 6 Evaporator A can operate stably in acidic, alkaline, and organic solutions. SEM images of the superhydrophobic sponge, superhydrophilic sponge, and original polyurethane sponge prepared in this invention are shown below. Figure 7 This invention expands the actual evaporation area by arranging modified hydrophilic and hydrophobic sponges at intervals to form multiple cold evaporation surfaces inside the evaporator. The trapezoidal arrangement at the top and the grooved structure at the bottom significantly improve the photothermal conversion performance and thermal management capabilities of the evaporator, thereby achieving a higher evaporation rate. The variation in evaporation rate is shown in [the figure]. Figure 8 Furthermore, a 7-day continuous evaporation test was conducted, and its evaporation rate remained stable. Figure 9 Seawater from the East China Sea was evaporated, and the concentrations of major ions in the water before and after evaporation were measured. (See attached data.) 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 merely some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of this invention should be considered within the scope of protection of this invention.

Claims

1. A three-dimensional trapezoidal seawater evaporator with alternating hydrophilic and hydrophobic sponge phases, characterized in that, The trapezoidal seawater evaporator comprises three hydrophilic sponges and two hydrophobic sponges, which are arranged alternately in a trapezoidal pattern. The top hydrophilic sponge forms a trapezoidal structure with a height difference, while the bottom hydrophobic sponge forms a groove structure. Two copper wires are threaded and fixed through connecting holes to form a three-dimensional trapezoidal hydrophilic-hydrophobic spaced sponge evaporator. The hydrophilic sponges are modified with polyvinyl alcohol, tannic acid, and iron ions, exhibiting good photothermal effects and superhydrophilicity. The hydrophobic sponges are modified with carbon nanotubes and polydimethylsiloxane, exhibiting high thermal conductivity and superhydrophobicity. The method for preparing the hydrophilic sponge includes the following steps: 1) First, wash the sheet 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) Soak the cleaned sponge in solution 1 and sonicate it, dry it, then soak it in solution 2 and sonicate it again, and then wash it with distilled water to obtain a superhydrophilic sponge. The method for preparing the hydrophobic sponge includes the following steps: 1) First, wash the sheet polyurethane sponge with distilled water and dry it for later use; 2) Using hexane as a solvent, polydimethylsiloxane and curing agent were added to hexane and stirred to obtain solution 3; carbon nanotubes were added to solution 3 and stirring was continued, and then the cleaned polyurethane sponge was soaked in the above solution; 3) Dry the soaked sponge to obtain a superhydrophobic sponge.

2. The three-dimensional trapezoidal seawater evaporator with alternating hydrophilic and hydrophobic sponge phases as described in claim 1, 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.

3. A three-dimensional trapezoidal seawater evaporator with alternating hydrophilic and hydrophobic sponge phases as described in claim 1, characterized in that, In step 3) of the preparation method of the hydrophilic sponge, the weight ratio of tannic acid to water is 3:

97.

4. A three-dimensional trapezoidal seawater evaporator with alternating hydrophilic and hydrophobic sponge phases as described in claim 1, characterized in that, In step 2) of the preparation method of the hydrophobic sponge, the curing agent is Condorcet SYLGARD 184, and the weight ratio of polydimethylsiloxane to curing agent is 10:

1.

5. A three-dimensional trapezoidal seawater evaporator with alternating hydrophilic and hydrophobic sponge phases as described in claim 1, characterized in that, In step 2) of the preparation method of the hydrophobic sponge, the weight-volume ratio of carbon nanotubes: polydimethylsiloxane: n-hexane is 2g: 2g: 20ml.

6. The application of the three-dimensional trapezoidal seawater evaporator with alternating hydrophilic and hydrophobic sponge phases as described in claims 1-5 in the field of seawater evaporation.

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