Array type 3D solar interface evaporator and preparation method and application thereof

Abstract

The invention relates to the field of water treatment, and particularly discloses an array type 3D solar interface evaporator and a preparation method and application thereof.The evaporator comprises a heat insulation supporting plate used for floating on the water surface, a plurality of cylindrical evaporation parts used for seawater evaporation are arranged on the upper surface of the heat insulation supporting plate, and the cylindrical evaporation parts are copper ammonia fiber membranes. The array type 3D solar interface evaporator has remarkable stability, mass transfer of water can be enhanced through a porous structure built inside, a sodium chloride solution is effectively prevented from forming crystals on the surface of the evaporator, and therefore the influence of salt crystallization on the evaporation performance of the evaporator is relieved. In addition, even if the evaporator is circularly operated for 8 times in high-salt water with the concentration of 15wt.%, the stable operation effect of the evaporator can still be kept. Therefore, the prepared array type 3D solar interface evaporator can effectively inhibit salt ion crystallization in the seawater desalination process, and has wide application prospects.

Description

Technical Field

[0001] The present invention relates to the field of solar seawater desalination, and in particular to an array-type 3D solar evaporator for seawater desalination, and a preparation method and application thereof. Technical Background

[0002] With population growth and accelerating economic development, freshwater shortages are receiving increasing attention. Given the abundance of seawater resources, desalination has become a key approach to alleviating this shortage. However, traditional desalination technologies, such as reverse osmosis and electrodialysis, still face challenges such as high energy consumption and environmental pollution. In recent years, solar interfacial evaporation technology has attracted widespread attention and intensive research in academia and industry due to its simplicity, environmental friendliness, and lack of additional energy consumption.

[0003] Currently, in order to improve the evaporation rate and efficiency of seawater desalination, researchers have been working to optimize the evaporator structure and develop high-performance photothermal materials to achieve efficient photothermal conversion. However, the existing two-dimensional planar evaporator has almost reached its theoretical evaporation limit (1.47 kg m -2 h -1 ), so many researchers turned their attention to three-dimensional solar evaporators. Although three-dimensional evaporators have high evaporation rates, in actual operation, most technicians still ignore the impact of salt crystallization on the evaporation process. During the continuous high-rate evaporation process, once the inorganic salt ions reach a saturated state, salt crystals will form on the surface of the evaporator, which not only hinders the light absorption of the solar evaporator, but also blocks the aperture, affecting the water transmission during the evaporation process, thereby limiting the long-term stable operation of the solar desalination system. Therefore, it is of great significance to develop a three-dimensional solar interface evaporator that can maintain efficient evaporation in high-concentration brine and achieve long-term stable operation. Summary of the Invention

[0004] To address operational shortcomings of existing three-dimensional solar evaporators, this invention aims to provide an array-type 3D solar interface evaporator for seawater desalination, along with its preparation method and application. This invention aims to address existing desalination technologies, such as low evaporation rates and the inability of the evaporator to operate stably over a long period of time due to surface crystallization, thereby increasing freshwater production.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides an array-type 3D solar interface evaporator for seawater desalination, comprising a heat-insulating support plate for floating on the sea surface, wherein the upper surface of the heat-insulating support plate vertically extends upward and is provided with a plurality of columnar evaporation components for evaporating seawater, wherein the columnar evaporation components extend downward through the lower surface of the heat-insulating support plate toward the seawater to form a guide end for transmitting seawater to the top of the columnar evaporation component, wherein the columnar evaporation component has a light-to-heat conversion layer and is hydrophilic; the plurality of columnar evaporation components are distributed in a ring array on the heat-insulating support plate.

[0007] Furthermore, the columnar evaporation component is a cuprammonia fiber membrane with a porous structure. The cuprammonia fiber membrane has porous channels for steam diffusion during the evaporation process, and is used for seawater transmission and steam dissipation.

[0008] Furthermore, the cuprammonium fiber membrane has a diameter of 30 to 50 mm and a height of 5 to 8 cm.

[0009] Furthermore, the height of the columnar evaporation component (the distance between the highest point of the evaporation component and the heat insulation support plate) is 3 to 5 cm. The diameter of the annular array is 1 to 4 cm.

[0010] Furthermore, the heat-insulating support plate is foam that has heat-insulating properties and can float on the water surface, including polyethylene foam, melamine foam, polyurethane foam, etc.

[0011] Furthermore, the heat insulation support plate can be cut as needed.

[0012] Furthermore, the method for preparing the cuprammonia fiber membrane comprises the following steps:

[0013] (1) dispersing basic copper carbonate in concentrated ammonia water with a concentration of 30 wt.% to 40 wt.% and ultrasonically treating the solution for 10 to 20 minutes to obtain solution A;

[0014] (2) Add medical absorbent cotton to solution A and stir for 20 to 30 minutes until the absorbent cotton is completely dissolved in solution A to obtain mixed solution B;

[0015] (3) adding a carbon nanotube aqueous slurry having a concentration of 13 to 15 wt.% to the mixed solution B, and stirring the mixture for 5 to 10 minutes to obtain a mixed solution C;

[0016] (4) Pour the mixed solution C into a needle tube and squeeze it into a dilute sulfuric acid solution under the action of a spinning needle, and let it stand at room temperature for 5 to 10 hours to obtain cuprammonia fiber;

[0017] (5) Rinse the cuprammonium fiber membrane prepared in step (4) with deionized water.

[0018] Furthermore, in step (1), the ratio of basic copper carbonate to concentrated ammonia water is 2-5 g: 20-50 mL. For example, the mass of basic copper carbonate is 2-5 g, and the volume of concentrated ammonia water is 20-50 mL.

[0019] Furthermore, in step (2), the mass ratio of the medical absorbent cotton to basic copper carbonate is 1 to 3: 2 to 5. For example, the mass of the medical absorbent cotton is 1 to 3 g.

[0020] Furthermore, in step (2), the stirring speed is 600 to 1000 rpm.

[0021] Furthermore, in step (3), the volume ratio of the carbon nanotube aqueous slurry to concentrated ammonia water is 0.5-1:20-50. For example, the volume of the carbon nanotube aqueous slurry is 0.5-1 mL.

[0022] Furthermore, in step (3), the stirring speed is 600 to 1000 rpm.

[0023] Furthermore, in step (4), the diameter of the spinning needle is 30 to 50 mm, and the concentration of the dilute sulfuric acid solution is 1 to 3 mol / L.

[0024] Furthermore, in step (4), the prepared cuprammonium fiber membrane is rinsed with deionized water for 3 to 5 times.

[0025] The present invention also provides a method for preparing the array-type 3D solar interface evaporator, comprising the following steps:

[0026] (1) Insert the cuprammonium fiber membrane onto the heat insulation support plate in sequence and extend it downward through the heat insulation support plate;

[0027] (2) The copper-ammonia fiber membrane prepared above the thermal insulation support plate is adjusted to obtain an array-type 3D solar interface evaporator consisting of a columnar evaporation component and a thermal insulation support plate.

[0028] Furthermore, in step (1), the prepared cuprammonium fiber membrane is cut into columns with a height of 5 to 8 cm for standby use.

[0029] Furthermore, in step (1), a groove is first opened on the heat-insulating support plate, and then the cuprammonium fiber membranes are vertically inserted into the grooves one by one until the grooves are filled and extend downward through the heat-insulating support plate.

[0030] Furthermore, in step (2), the height of the cuprammonium fiber membrane above the thermal insulation support plate is adjusted to 3 to 5 cm.

[0031] Furthermore, in step (2), the cuprammonium fiber membrane prepared above the thermal insulation support plate is adjusted to the same height.

[0032] The present invention also provides an application of the above-mentioned array 3D solar interface evaporator in seawater desalination, which is suitable for treating saline wastewater, especially high-concentration saline wastewater (salt concentration range is 3.5wt.% to 20wt.%).

[0033] The array-type 3D solar interface evaporator prepared by the present invention has significant stability. The porous structure constructed internally can enhance the mass transfer of water, effectively preventing the formation of crystals of sodium chloride solution on the surface of the evaporator, thereby alleviating the impact of salt crystallization on the evaporation performance of the evaporator.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention provides an array-type 3D solar interface evaporator and its preparation method and application. The evaporator consists of a heat-insulating support plate and a cuprammonium fiber membrane serving as a water supply and steam escape channel. The cuprammonium fiber membrane in the present invention has an excellent porous structure, which can ensure sufficient water flow support during the seawater desalination process. In addition, the 3D structure significantly increases the specific surface area of ​​the evaporator, which is conducive to the efficient escape of steam. More importantly, due to the difference in energy acquisition between the upper and lower parts of the array evaporator, a temperature gradient is formed, thereby inducing Marangoni convection, and the high-concentration brine generated in the desalination process is re-dissolved back into the resource water through the internal porous channels, effectively alleviating the impact of salt crystallization on the long-term stable operation of the evaporator. After testing, at a light intensity of 1kW m -2 Under the condition of 20 wt.% high-salinity wastewater, the evaporator achieved a 2.53 kg m -2 h -1 The evaporator maintained stable operation even after eight cycles in a 15wt.% saline solution. Therefore, the arrayed 3D solar interface evaporator fabricated in this invention effectively inhibits salt ion crystallization during seawater desalination, demonstrating its broad application prospects in solar desalination and high-concentration brine treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0037] Figure 1 This is a physical picture of the convection 3D solar interface evaporator prepared in Example 1;

[0038] Figure 2 This is an SEM image of the convective 3D solar interface evaporator prepared in Example 1;

[0039] Figure 3 This is the infrared spectrum of the convection 3D solar interface evaporator prepared in Example 1;

[0040] Figure 4 This is a graph showing the change in water evaporation rate of the convective 3D solar interface evaporator prepared in Example 1 under different solar radiation intensities;

[0041] Figure 5 This is a graph showing the evaporation rate of salt solutions of different concentrations processed by the convective 3D solar interface evaporator prepared in Example 1;

[0042] Figure 6 This is a graph of the evaporation rate of the convective 3D solar interface evaporator prepared in Example 1 after 8 cycles of operation in a brine with a concentration of 15 wt.% sodium chloride. DETAILED DESCRIPTION

[0043] The following non-limiting examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0044] The evaporation rate determination method in the following examples is as follows:

[0045] An array of 3D solar interface evaporators was placed in a solar lighting system equipped with an AM1.5G spectral filter to construct a solar evaporation device. During the evaporation experiment, an electronic balance with an accuracy of 0.0001g was used to record mass changes in real time, and a computer connected to the balance collected relevant data. The evaporation rate was calculated according to formula (1).

[0046]

[0047] Where v is the evaporation rate of water (kg m -2 h -1 ), m is the evaporation mass of water (kg), S is the projected area of ​​evaporator (m 2 ), t is the evaporation time (h).

[0048] Example 1

[0049] An array-type 3D solar interface evaporator comprises an insulating support plate for floating on the sea surface. The insulating support plate has a lower surface for contact with seawater and an upper surface corresponding thereto. The insulating support plate is constructed of polyethylene foam. Several cylindrical evaporation components for seawater evaporation are vertically inserted upward from the upper surface of the insulating support plate. These cylindrical evaporation components extend downward through the lower surface of the insulating support plate to form guide ends for seawater transmission. The cylindrical evaporation components are constructed of cuprammonia fiber membranes and are distributed in a circular array on the insulating support plate.

[0050] The method for preparing the cuprammonia fiber membrane comprises the following steps:

[0051] 4g of basic copper carbonate was dispersed in 40mL of 35wt% concentrated ammonia water and ultrasonically treated for 10 minutes to obtain a mixed dispersion. 2g of medical cotton wool was added to the mixed dispersion and stirred at 700rpm for 25 minutes. After the cotton wool was completely dissolved in the mixture, 0.8mL of a 14wt% carbon nanotube aqueous slurry (Xianfeng Nano, Zhejiang) was added and stirred at 800rpm for 25 minutes to obtain a spinning solution. The spinning solution was poured into a 20mL syringe and manually squeezed into 1000mL of 1mol / L dilute sulfuric acid solution using a 30mm diameter spinning needle. The solution was then allowed to stand at room temperature of 25°C for 8 hours to produce a copper ammonia fiber membrane. The resulting copper ammonia fiber membrane was then rinsed three times with deionized water and cut into 5cm tall cylinders for later use.

[0052] The preparation method of the array-type 3D solar interface evaporator comprises the following steps:

[0053] Polyethylene foam was cut into cubes with a length, width, and height of 6 cm, 6 cm, and 2 cm, respectively. A circular groove with a diameter of 3 cm was chiseled out on the top of the polyethylene foam. Subsequently, the cut cuprammonium fiber membranes were vertically inserted into the grooves of the polyethylene foam one by one until the grooves were filled and extended downward through the polyethylene foam. After adjusting the height of the cuprammonium fiber membrane above the polyethylene foam to 3 cm, an array-type 3D solar interface evaporator was prepared (see Figure 1 ), named CNT / Cupro.

[0054] Figure 1 A physical picture of the preparation of an array 3D solar interface evaporator;

[0055] Figure 2 The scanning electron microscopy results of the prepared cuprammonia fiber membrane are shown. As can be seen from the electron microscopy image, the cuprammonia fiber membrane has a porous structure, which helps to provide sufficient water supply in the seawater desalination process.

[0056] Figure 3 The light absorption capacity of the prepared cuprammonium fiber membrane was measured using an ultraviolet-visible-near-infrared spectrophotometer within the solar spectrum range of 250 to 2500 nm. The results showed that the cuprammonium fiber membrane achieved a broad-band absorption of approximately 97.75% across the entire solar spectrum, which facilitates efficient photothermal conversion and solar steam generation in the subsequent evaporation process.

[0057] The prepared array 3D solar interface evaporator was placed under different sunlight intensities (1 kWm -2 ,2kW m -2 and 3kW m -2 ) to test its evaporation rate of pure water. Figure 4 As shown, when the light intensity is 1kW m -2 ,2kWm -2 , and 3kW m -2 The corresponding evaporation rates are 3.63 ± 0.03 kg m -2 h -1 , 4.2±0.015kg m -2 h -1 , and 4.85±0.08kg m -2 h -1 .

[0058] Example 2

[0059] The main difference between this embodiment and Example 1 is that under the condition of 1 solar intensity (1kW m -2 ) was used to measure the evaporation rate of the prepared array-type 3D solar interface evaporator for brine of different concentrations (the concentrations of sodium chloride solution were 3.5wt.%, 5wt.%, 15wt.% and 20wt.%), and the other conditions were the same as those in Example 1.

[0060] Salt crystallization resistance test, evaporation rate results are shown in Figure 5 .from Figure 5 It can be seen that at a solar intensity (1kWm -2 ), when the concentrations of sodium chloride solution were 3.5wt.%, 5wt.%, 15wt.%, and 20wt.%, respectively, the evaporation rates of the prepared solar evaporator were 3.42±0.09kg m -2 h -1 3.15±0.03kg m -2 h -1 , 2.82±0.06kg m - 2 h -1 , and 2.53±0.03kg m -2 h -1 .

[0061] Example 3

[0062] The main difference between this embodiment and Example 1 is that under the condition of 1 sunlight intensity (1kW m -2 ) was used to measure the evaporation rate of the prepared array-type 3D solar interface evaporator after 8 cycles in a sodium chloride solution with a concentration of 15 wt.%. After each cycle test, the array-type 3D solar interface evaporator was rinsed with deionized water before the next cycle test was performed. The other conditions were the same as in Example 1.

[0063] like Figure 6As shown in Figure 2, the evaporation rate of the prepared array 3D solar interface evaporator can still be maintained at 2.75 kg m after 8 cycles. -2 h -1 This is because during the evaporation process, the porous structure of the evaporator can transmit sufficient water to support the dissolution of salt during the evaporation process. At the same time, the Marangoni effect induced by the temperature gradient accelerates fluid exchange, continuously diluting the high-concentration brine formed by evaporation on the evaporator surface, preventing the precipitation of sodium chloride crystals on the evaporator surface, thereby alleviating the impact of salt crystallization on the evaporation performance of the evaporator to a certain extent.

Claims

1. An array-type 3D solar evaporator for seawater desalination, characterized by: It includes a heat-insulating support plate for floating on the sea surface. The upper surface of the heat-insulating support plate vertically extends upward to form a plurality of porous columnar evaporation components for evaporating seawater. The columnar evaporation components extend downward through the lower surface of the heat-insulating support plate toward the seawater to form a guide end for transmitting seawater to the top of the evaporation component. The columnar evaporation component has a light-to-heat conversion layer and is hydrophilic. The plurality of columnar evaporation components are distributed in a ring array on the heat-insulating support plate.

2. The array-type 3D solar interface evaporator for seawater desalination according to claim 1, characterized in that: The columnar evaporation component is a cuprammonia fiber membrane with a porous structure; the heat insulation support plate is a heat insulation foam, including melamine foam, metal foam or polyurethane foam.

3. The array-type 3D solar interface evaporator for seawater desalination according to claim 1, characterized in that: The diameter of the cuprammonia fiber membrane is 30-50 mm, and the height is 5-8 cm.

4. The array-type 3D solar interface evaporator for seawater desalination according to claim 1, characterized in that: The diameter of the annular array is 1 to 4 cm.

5. The array-type 3D solar interface evaporator for seawater desalination according to claim 1, characterized in that: The height of the columnar evaporation component is 3 to 5 cm.

6. The array-type 3D solar interface evaporator for seawater desalination according to claim 2, characterized in that: The method for preparing the cuprammonia fiber membrane comprises the following steps: (1) dispersing basic copper carbonate in concentrated ammonia water with a concentration of 30 wt.% to 40 wt.% and ultrasonically treating the solution for 10 to 20 minutes to obtain solution A; (2) Add medical absorbent cotton to solution A and stir for 20 to 30 minutes until the absorbent cotton is completely dissolved in solution A to obtain mixed solution B; (3) adding a carbon nanotube aqueous slurry having a concentration of 13 to 15 wt.% to the mixed solution B and stirring the mixture for 5 to 10 minutes to obtain a mixed solution C; (4) Pour the mixed solution C into a needle tube and squeeze it into a dilute sulfuric acid solution under the action of a spinning needle, and let it stand at room temperature for 5 to 10 hours to obtain a cuprammonium fiber membrane; (5) Rinse the cuprammonium fiber membrane prepared in step (4) with deionized water.

7. The array-type 3D solar interface evaporator for seawater desalination according to claim 6, characterized in that: In step (1), the ratio of basic copper carbonate to concentrated ammonia water is 2-5 g: 20-50 mL; In step (2), the mass ratio of the medical absorbent cotton to basic copper carbonate is 1-3:2-5, and the stirring speed is 600-1000 rpm; In step (3), the volume ratio of the carbon nanotube aqueous slurry to concentrated ammonia water is 0.5-1:20-50, and the stirring speed is 600-1000 rpm; In step (4), the diameter of the spinning needle is 30 to 50 mm, and the concentration of the dilute sulfuric acid solution is 1 to 3 mol / L.

8. The method for preparing an array-type 3D solar interface evaporator for seawater desalination according to any one of claims 1 to 7, characterized in that: The steps include: (1) Insert the cuprammonium fiber membrane onto the heat insulation support plate in sequence and extend it downward through the heat insulation support plate; (2) Adjusting the height of the prepared copper-ammonia fiber membrane above the thermal insulation support plate to obtain an array-type 3D solar interface evaporator.

9. The preparation method according to claim 8, characterized in that In step (1), a groove is first formed on the heat-insulating support plate, and then the cuprammonium fiber membranes are vertically inserted into the grooves one by one until the grooves are filled and extend downward through the heat-insulating support plate; In step (2), the height of the cuprammonium fiber membrane above the thermal insulation support plate is adjusted to 3 to 5 cm.

10. Use of the arrayed 3D solar interface evaporator according to any one of claims 1 to 7 in seawater desalination.

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