Large scale production of planar cocoon evaporators with laterally layered janus structures and methods and applications

Abstract

The application discloses a plane cocoon evaporator with large-scale production of transverse layered Janus structure and a method and application thereof. The method comprises the following steps: coating super-hydrophilic polypyrrole on the surface of the plane cocoon, coating super-hydrophobic PDMS on the top, and transforming the plane cocoon into a Janus structure evaporator; the transverse layered fiber Janus structure enables the evaporator to transport water to the super-hydrophilic / hydrophobic interface through the bottom and evaporate without salt precipitation; the top absorbs solar energy and transmits heat to the bottom in the evaporator, high-efficiency evaporation maximally reduces heat loss, and the high evaporation rate and evaporation efficiency of the plane cocoon evaporator enable it to continuously evaporate in a high-salt solution without salt deposition under sunlight. The application large-scale prepares a Janus solar seawater evaporator through a simple immersion and spraying method, solves the large-scale preparation problem of the transverse layered structure evaporator, and is an environment-friendly, economical, salt-resistant and heat-positioning evaporator, which is expected to be large-scale applied in seawater desalination.

Description

Technical Field

[0001] This invention relates to the field of interface processing technology, and specifically to a planar cocoon evaporator with a horizontally layered Janus structure that can be mass-produced, as well as its method and application. Background Technology

[0002] The growing scarcity of freshwater underscores the importance of research into seawater desalination using solar-powered evaporators. Traditional solar evaporators prioritize high evaporation rates; however, prolonged evaporation leads to salt crystal accumulation on the surface, hindering sunlight absorption and reducing the evaporation rate. Janus evaporators, characterized by their hydrophobic and hydrophilic layers, address this challenge. The hydrophobic layer facilitates the absorption of sunlight to generate heat, while the hydrophilic layer aids water transport, reducing heat loss and the risk of crystallization by preventing direct contact between the evaporator layer and the water column. However, salt crystal formation at the hydrophobic-hydrophilic interface still hinders the evaporation rate and long-term salt resistance of Janus evaporators. Combining a transversely layered structure with the Janus design further reduces heat loss and crystallization risk. However, current manufacturing methods primarily rely on 3D printing and ice crystal templates, lacking a sustainable and direct method for large-scale production of transversely layered Janus structure evaporators using environmentally friendly materials.

[0003] Planar cocoons are a natural silk derivative, a unique three-dimensional layered porous material characterized by the stacking of two-dimensional fiber webs on a flat surface through continuous silkworm spinning. Notably, due to their inherent porous, laterally layered structure, planar cocoons offer advantages in terms of availability, cost-effectiveness, and scalable production. The loose, multi-layered, and porous structure of planar cocoons facilitates efficient water transport, while their natural laterally layered structure contributes to improved heat resistance. Combined with their economic viability and availability, planar cocoons demonstrate high practicality and cost-effectiveness when used in laterally layered Janus evaporators. Summary of the Invention

[0004] To address the problems existing in the background art, the present invention provides a planar cocoon evaporator with a transversely layered Janus structure that can be mass-produced, as well as a method and application thereof.

[0005] The technical solution adopted in this invention is:

[0006] I. A method for preparing a planar cocoon evaporator with a transversely layered Janus structure that can be mass-produced, comprising the following steps:

[0007] (1) Using the flat cocoon formed by the fifth instar larvae of silkworm spinning silk on a flat substrate as raw material, by controlling the spinning area and time, a large area flat cocoon substrate with controllable size can be obtained.

[0008] (2) Place the flat cocoon substrate in deionized water, add pyrrole monomer, phosphoric acid solution and ferric chloride in sequence, shake continuously to react and then let stand;

[0009] (3) The planar cocoon substrate treated in step (2) is then rinsed with ethanol-water alternately and dried to obtain a polypyrrole-loaded planar cocoon composite material;

[0010] (4) Use a spray gun to spray PDMS solution at a certain distance from the surface of the planar cocoon composite material. The PDMS solution forms a hydrophobic layer on the surface of the planar cocoon composite material. The thickness of the hydrophobic layer is controlled by adjusting the amount of spraying per spray and the number of sprayings.

[0011] (5) The sprayed planar cocoon composite material is heat-cured to obtain a planar cocoon evaporator with a transverse layered Janus structure.

[0012] The specific steps (2) are as follows: Place the planar cocoon substrate in 30 mL of deionized water and then add pyrrole monomer, phosphoric acid solution and ferric chloride in sequence. After continuous shaking reaction for 6 hours, let it stand.

[0013] The concentration of the pyrrole monomer in the system is 0.003–0.03 mol / L, the volume concentration of the phosphoric acid solution in the system is 0.03%, and the molar ratio of the pyrrole monomer to the ferric chloride is 1:1–1:2.

[0014] The system is a reaction system formed by mixing deionized water, pyrrole monomer and ferric chloride.

[0015] The specific step (3) is as follows: the planar cocoon substrate treated in step (2) is rinsed with ethanol-water alternately 5 times and dried to obtain a planar cocoon composite material loaded with polypyrrole.

[0016] In step (4), the hydrophobic layer is formed by spraying PDMS solution onto one side of the bottom / top of the planar cocoon composite material.

[0017] The PDMS mentioned in step (4) is a mixture of PDMS prepolymer and PDMS curing agent at a mass ratio of 10:1.

[0018] In step (4), the spraying distance is 5-8 cm, and the spraying amount is 0.125 mL / cm every 3 seconds. 2 The number of spraying times is 1.

[0019] The specific step (5) is as follows: the sprayed planar cocoon composite material is heat-cured in an oven at 80-100℃ for 0.5-2h to obtain a planar cocoon evaporator with a transverse layered Janus structure.

[0020] II. A planar cocoon evaporator with a transversely layered Janus structure that can be mass-produced is made using the above-described preparation method.

[0021] III. Application of the mass-producible planar cocoon evaporator with a horizontally layered Janus structure in seawater desalination evaporation.

[0022] This invention transforms a planar cocoon into a Janus-structured evaporator by coating the entire surface of the cocoon with superhydrophilic polypyrrole and spraying superhydrophobic PDMS on the top. The laterally layered fiber Janus structure enables the evaporator to efficiently and rapidly transport water to the superhydrophilic / hydrophobic interface through its bottom, evaporating without salt precipitation. At the same time, the top absorbs solar energy and transfers heat to the bottom inside the evaporator, promoting efficient evaporation while minimizing heat loss. The high evaporation rate and efficiency of the planar cocoon evaporator allow it to continuously evaporate in high-salt solutions without salt deposition under sunlight.

[0023] The beneficial effects of this invention are:

[0024] This invention utilizes planar cocoons of controllable size to fabricate Janus solar seawater evaporators on a large scale through a simple wetting and spraying method, and demonstrates that the evaporator possesses a superhydrophobic top layer and a superhydrophilic bottom layer structure, thus solving the problem of large-scale fabrication of horizontal sheet-like evaporators.

[0025] The planar cocoon evaporator with a transversely layered Janus structure of the present invention has an evaporation capacity of 3.075 kg m²h. -1 With an evaporation efficiency of 79.73%, it can continuously evaporate in a 20% salt solution for 18 hours without salt deposition under sunlight. This invention's transversely layered Janus structure planar cocoon evaporator represents a new generation of environmentally friendly, economical, salt-resistant, and thermally positioned evaporators, with the potential for large-scale practical application in seawater desalination. Attached Figure Description

[0026] Figure 1 The images show the SEM cross-sectional view (A), top view (B), bottom view (C), contact angle images of the top and bottom, and cross-sectional EDS elemental analysis diagram for Example 3. The insets are enlarged views.

[0027] Figure 2 As in Example 3, in the (A) water environment of Comparative Examples 3 and 6, under a light intensity of 1 kW m², -2 (A) Temperature photograph after 60 minutes of continuous irradiation, (B) Evaporation rate change over 60 minutes, (C) Comparison of evaporation efficiency and evaporation rate.

[0028] Figure 3As in Example 3, Comparative Examples 3 and 6, (A) simulated seawater concentration (3.5 wt% - 20 wt%) with a light intensity of 1 kW m² -2 Evaporation rate graph, (B) Photograph of continuous salt-tolerant evaporation at 20 wt% salt concentration in Example 3 and Comparative Example 3. Detailed Implementation

[0029] The present invention will be further described below with reference to the embodiments and accompanying drawings. The following embodiments are only preferred embodiments of the present invention and do not limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0030] Experimental methods not specifically described in the following examples are generally determined according to national standards; if no corresponding national standard exists, they are performed according to generally accepted international standards or the standards proposed by relevant enterprises. Unless otherwise stated, all parts are parts by weight, and all percentages are weight percentages.

[0031] The embodiments of the present invention are as follows:

[0032] Example 1

[0033] This embodiment describes a method for preparing a planar cocoon evaporator with a transversely layered Janus structure that can be mass-produced, comprising the following steps:

[0034] (1) Place the flat cocoon substrate (4cm×4cm) in 30mL of deionized water.

[0035] (2) Add 1 mmol of pyrrole monomer, 1 mL of 1% phosphoric acid solution and 1 mmol of ferric chloride in sequence, shake continuously for 6 hours and then let stand.

[0036] (3) After being rinsed with ethanol-water alternately 5 times and dried, a planar cocoon composite material loaded with polypyrrole was obtained;

[0037] (4) Use a spray gun to spray PDMS solution at a distance of 5 cm from the surface of the planar cocoon composite material;

[0038] (5) Spray 2 mL of PDMS solution evenly within 3 seconds each time, and spray once in total;

[0039] (6) After spraying, the coating is cured in an oven at 80°C for 30 minutes to obtain a planar cocoon evaporator with a transverse layered Janus structure.

[0040] Example 2

[0041] (1) Place the flat cocoon substrate (size 4cm×4cm) in 30mL of deionized water;

[0042] (2) Add 5 mmol of pyrrole monomer, 1 mL of 1% phosphoric acid solution and 5 mmol of ferric chloride in sequence, shake continuously for 6 hours and then let stand.

[0043] (3) After being rinsed with ethanol-water alternately 5 times and dried, a planar cocoon composite material loaded with polypyrrole was obtained;

[0044] (4) Use a spray gun to spray PDMS solution at a distance of 5 cm from the surface of the planar cocoon composite material;

[0045] (5) Spray 2 mL of PDMS solution evenly within 3 seconds each time, and spray once in total;

[0046] (6) After spraying, the coating is cured in an oven at 80°C for 30 minutes to obtain a planar cocoon evaporator with a transverse layered Janus structure.

[0047] Example 3

[0048] (1) Place the flat cocoon substrate (size 4cm×4cm) in 30mL of deionized water;

[0049] (2) Add 7 mmol of pyrrole monomer and 1 mL of 1% phosphoric acid solution and 7 mmol of ferric chloride in sequence, shake continuously for 6 hours and then let stand.

[0050] (3) After rinsing with ethanol-water alternately five times and drying, a polypyrrole-loaded planar cocoon composite material was obtained.

[0051] (4) Use a spray gun to spray PDMS solution at a distance of 5 cm from the surface of the planar cocoon composite material;

[0052] (5) Spray 2 mL of PDMS solution evenly within 3 seconds each time, and spray once in total;

[0053] (6) After spraying, the coating is cured in an oven at 80°C for 30 minutes to obtain a planar cocoon evaporator with a transverse layered Janus structure.

[0054] Comparative Example 1

[0055] The preparation method of the planar cocoon evaporator with a transversely layered Janus structure that can be mass-produced in this comparative example is the same as that in Example 1, except that steps 4 and 5 are not performed.

[0056] Comparative Example 2

[0057] The preparation method of the planar cocoon evaporator with a transversely layered Janus structure that can be mass-produced in this comparative example is the same as that in Example 2, except that steps 4 and 5 are not performed.

[0058] Comparative Example 3

[0059] The preparation method of the planar cocoon evaporator with a transversely layered Janus structure that can be mass-produced in this comparative example is the same as that in Example 3, except that steps 4 and 5 are not performed.

[0060] Comparative Example 4

[0061] The preparation method of the planar cocoon evaporator with a transversely layered Janus structure that can be mass-produced in this comparative example is the same as that in Example 1, except that step 5 involves spraying the coating three times.

[0062] Comparative Example 5

[0063] The preparation method of the planar cocoon evaporator with a transversely layered Janus structure that can be mass-produced in this comparative example is the same as that in Example 2, except that step 5 involves spraying the coating three times.

[0064] Comparative Example 6

[0065] The preparation method of the planar cocoon evaporator with a transversely layered Janus structure that can be mass-produced in this comparative example is the same as that in Example 3, except that step 5 involves spraying the coating three times.

[0066] Figure 1 The contact angles of the top and bottom of Example 3 Figure 1 D, SEM cross-section Figure 1 A, Top Figure 1 B and bottom image - Figure 1 C, and the EDS elemental analysis diagram of the cross-section - Figure 1 Composed of E. (The rest of the text appears to be a list of components or abbreviations and can be left untranslated.) Figure 1 The SEM images show that the Janus evaporator is a porous, layered evaporator. The difference in Si elemental distribution from EDS elemental analysis proves that the Janus evaporator of Example 3 has differences in PDMS composition between the top and bottom layers. Therefore, the contact angle photographs of the top and bottom layers demonstrate the hydrophilic and hydrophobic differences between the top and bottom layers of Example 3.

[0067] The top and bottom contact angles and light intensity of the products in the above embodiments and comparative examples were tested in a pure water environment at 1 kW m². -2 The temperature was determined by irradiation for 60 minutes, and the results are shown in Table 1 below.

[0068] Table 1. Top and bottom contact angles and light intensities (1 kWm) of the examples and comparative products. -2 Temperature after continuous irradiation for 60 minutes

[0069]

[0070]

[0071] As shown in Table 1, with increasing pyrrole content, the top and bottom contact angles of Comparative Examples 4, 5, and 6 gradually increased, exhibiting a change from hydrophobic to superhydrophobic, even with complete hydrophobic PDMS coating. Simultaneously, with increasing pyrrole content, the top and bottom contact angles of Comparative Examples 1, 2, and 3 gradually decreased to 0. This is because, without PDMS coating, the hydrophilic polypyrrole stacking resulted in a rough surface and a superhydrophilic state. Furthermore, with increasing pyrrole content, the top contact angle of Examples 1, 2, and 3 changed from hydrophobic to superhydrophobic, and the bottom contact angle changed from hydrophilic to superhydrophilic. This is due to the top layer being coated with hydrophobic PDMS while the bottom layer was not, demonstrating that these examples possess Janus characteristics.

[0072] As shown in Table 1, the temperatures of both the examples and the comparative examples increased with the increase in the amount of pyrrole added. However, due to the heat absorption of the water in the aquatic environment, the temperatures of Comparative Examples 1, 2, and 3 were lower than those of Comparative Examples 4, 5, and 6. Examples 1, 2, and 3 had higher temperatures than Comparative Examples 1, 2, and 3 because less heat was lost to the water due to the Janus property. Comparative Examples 4, 5, and 6 had the highest temperatures because they were completely superhydrophobic and there was no heat loss due to water contact.

[0073] The products of the above embodiments and comparative examples were subjected to light intensity of 1kW m² in a pure water environment. -2 The evaporation rate was calculated, and the results are shown in Table 2 below.

[0074] Table 2 Evaporation rates and efficiencies of the examples and comparative products

[0075]

[0076]

[0077] As shown in Table 2, the evaporation rate and evaporation efficiency of both the examples and the comparative examples increased with the increase of pyrrole addition. Furthermore, the examples, due to their Janus evaporator and stratification characteristics, exhibited higher evaporation rates and evaporation efficiencies than the comparative examples with the same pyrrole addition, verifying that the Janus evaporator possesses the optimal evaporation rate and efficiency. Figure 2 A, Figure 2 B and Figure 2 C shows temperature photographs, evaporation rate and efficiency graphs of Example 3, Comparative Examples 3 and 6 with the same amount of pyrrole added, demonstrating that Example 3 has the best evaporation effect due to the Janus properties.

[0078] The products of the above embodiments and comparative examples were subjected to simulated seawater concentrations (3.5 wt%) and concentrated seawater concentrations (10 wt%, 20 wt%) with a light intensity of 1 kW m². -2 The evaporation rate was calculated, and the results are shown in Table 3 below.

[0079] Table 3 Salt evaporation rates of the examples and comparative products

[0080]

[0081] Depend on Figure 3 As can be seen from A, under the same pyrrole addition amount, when the seawater concentration increased from 3.5 wt% to 20 wt%, Example 3 maintained a high and stable evaporation rate, which is due to the salt tolerance property of Janus. In contrast, the evaporation rate of Comparative Example 3 fluctuated and decreased with increasing salt concentration, and the evaporation rate was relatively low, while Comparative Example 6 maintained an extremely low evaporation rate. Figure 3 B shows photographs of continuous evaporation of Example 3 and Comparative Example 3 at a salt concentration of 20 wt%. It can be seen that Example 3 did not produce salt crystals for 18 hours, while Comparative Example 3 produced a large amount of crystals starting from 3 hours. This also demonstrates that the Janus property prevents salt crystal formation on the evaporator surface, maintaining efficient salt-resistant evaporation. Comparative Example 3, lacking the Janus property, experienced a lower evaporation rate due to the large amount of salt crystals blocking sunlight.

[0082] As shown in Table 3, the evaporation rates of the examples and comparative examples increased under different salt concentrations with increasing pyrrole addition. This is because the increased polypyrrole stacking leads to increased light absorption, which in turn increases the temperature and ultimately the evaporation rate. Simultaneously, the Janus and layered structure characteristics give the evaporator heat-blocking and salt-resistant properties. Therefore, the examples with the same pyrrole ratio have higher evaporation rates and efficiencies than the comparative examples, and the examples maintain high evaporation efficiency without decreasing the rate even at increasing salt concentrations. Comparative examples 1, 2, and 3, however, exhibited low evaporation rates and poor salt resistance due to significant heat loss and salt crystallization.

[0083] The above specific embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

[0084] The above description is only a preferred embodiment of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of this patent application are included in the scope of this patent application.

Claims

1. A method for preparing a planar cocoon evaporator with a transversely layered Janus structure capable of large-scale production, characterized in that, Includes the following steps: (1) Using the flat cocoon formed by the fifth instar larvae of silkworm spinning silk on a flat substrate as raw material, a flat cocoon substrate is prepared; (2) Place the planar cocoon substrate in deionized water, add pyrrole monomer, phosphoric acid solution and ferric chloride in sequence, shake continuously and let stand; (3) The planar cocoon substrate treated in step (2) is then rinsed with ethanol-water alternately and dried to obtain a polypyrrole-loaded planar cocoon composite material; (4) Use a spray gun to spray PDMS solution at a certain distance from the surface of the planar cocoon composite material. The PDMS solution is sprayed on one side of the planar cocoon composite material to form a hydrophobic layer. (5) The sprayed planar cocoon composite material is thermally cured to obtain a planar cocoon evaporator with a transverse layered Janus structure; the planar cocoon evaporator has a superhydrophobic top layer and a superhydrophilic bottom layer structure.

2. The method for preparing a planar cocoon evaporator with a transversely layered Janus structure capable of large-scale production according to claim 1, characterized in that: Step (2) specifically involves: The planar cocoon substrate was placed in 30 mL of deionized water, and then pyrrole monomer, phosphoric acid solution and ferric chloride were added in sequence. After continuous shaking for 6 h, the mixture was allowed to stand. The concentration of the pyrrole monomer in the system is 0.003~0.03 mol / L, the volume concentration of the phosphoric acid solution in the system is 0.03%, and the molar ratio of the pyrrole monomer to the ferric chloride is 1:1~1:2; The system is a reaction system formed by mixing deionized water, pyrrole monomer and ferric chloride.

3. The method for preparing a planar cocoon evaporator with a transversely layered Janus structure capable of large-scale production according to claim 1, characterized in that: The specific step (3) is as follows: the planar cocoon substrate treated in step (2) is rinsed with ethanol-water alternately 5 times and dried to obtain a planar cocoon composite material loaded with polypyrrole.

4. The method for preparing a planar cocoon evaporator with a transversely layered Janus structure capable of large-scale production according to claim 1, characterized in that: In step (4), PDMS is a mixture of PDMS prepolymer and PDMS curing agent at a mass ratio of 10:

1.

5. The method for preparing a planar cocoon evaporator with a transversely layered Janus structure capable of large-scale production according to claim 1, characterized in that: In step (4), the spraying distance is 5-8 cm, and the spraying amount is 0.125 mL / cm every 3 seconds. 2 The number of spraying times is 1.

6. The method for preparing a planar cocoon evaporator with a transversely layered Janus structure capable of large-scale production according to claim 1, characterized in that: The specific step (5) is as follows: the sprayed planar cocoon composite material is heat-cured in an oven at 80-100℃ for 0.5-2h to obtain a planar cocoon evaporator with a transverse layered Janus structure.

7. A planar cocoon evaporator with a transversely layered Janus structure capable of mass production, characterized in that, It is prepared by the preparation method described in any one of claims 1-6.

8. An application of a planar cocoon evaporator with a transversely layered Janus structure prepared by the preparation method according to any one of claims 1-6, characterized in that: Applications in seawater desalination and evaporation.

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