Solar evaporator for brine separation and 3d printing based method of fabrication thereof

Abstract

This invention discloses a solar evaporator for brine separation and its fabrication method based on 3D printing. The solar evaporator is fabricated using 3D printing and plasma cleaning technologies to achieve salt collection and water evaporation. The solar evaporator, from bottom to top, includes an open microchannel with a photothermal conversion coating on both surfaces, a water-collecting and salt-retaining structure, and a directional salt-deposition structure. The open microchannel has a porous structure, allowing the brine to flow and evaporate through capillary channels and a hydrophilic coating. The water-collecting and salt-retaining structure has a central water collection section and an outer salt collection section, separated by a baffle. The directional salt-deposition structure is located at the outer edge of the water collection section and is a cylindrical structure filled with a porous structure. In this invention, the liquid within each component of the evaporator can contact the external environment, effectively utilizing light and heat, significantly improving evaporation efficiency, and recovering salt scale while temporarily storing water.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and more specifically, to a solar evaporator for brine separation and its manufacturing method based on 3D printing. Background Technology

[0002] Researching green and low-carbon water treatment technologies is crucial for achieving the development goal of synergistic efficiency in pollution reduction and carbon reduction.

[0003] In zero (near-zero) emission treatment processes, the key is to reduce the volume of wastewater by increasing its salinity and reducing its volume, thereby lowering process energy consumption and costs. However, the volume reduction treatment of high-salinity wastewater requires a large amount of energy to achieve salt / water separation, resulting in carbon emissions far exceeding those of other industrial wastewater. Therefore, developing green and low-carbon wastewater concentration and volume reduction technologies is of great significance for achieving energy-efficient treatment of high-salinity wastewater and promoting the sustainable development of my country's economy.

[0004] Solar interfacial evaporation technology utilizes solar energy for localized photothermal evaporation on the evaporator surface to achieve efficient salt / water separation. It is widely recognized as a green, low-carbon, and sustainable concentration and separation technology, and has received extensive research and attention in recent years. However, during brine treatment, the salt scale precipitated on the photothermal evaporation surface leads to a sharp decline in the system's treatment performance, becoming a major bottleneck restricting the development and application of this technology. Furthermore, the recovery of salt, a byproduct of water treatment, is also a key issue that solar interfacial evaporation technology urgently needs to address. Summary of the Invention

[0005] To address the aforementioned deficiencies in existing technologies, this invention provides a solar evaporator for brine separation and its manufacturing method based on 3D printing. The solar evaporator is fabricated using 3D printing, thereby achieving salt collection and water evaporation.

[0006] To achieve the above objectives, on the one hand, the present invention provides a solar evaporator for brine separation, characterized in that it comprises, from bottom to top, an open microchannel, a water-collecting and salt-retaining structure, and a directional salt-separating structure; the surfaces of the open microchannel, the water-collecting and salt-retaining structure, and the directional salt-separating structure are all coated with a photothermal conversion coating.

[0007] The open microchannel has a porous structure, which allows for the diversion and evaporation of saline solution through capillary channels and a hydrophilic photothermal conversion coating;

[0008] The central part of the water storage and salt collection structure is the water collection section, and the outer part is the salt collection section; the water collection section and the salt collection section are separated by a baffle.

[0009] The directional salt precipitation structure is a porous cylindrical structure used for water evaporation and salt crystallization, and is inclined from the water collection part to the upper part of the salt collection part.

[0010] Furthermore, the open microchannel is a porous structure composed of multiple power rods and support rods; the power rods are evenly distributed on a base circle, and the support rods connect the power rods together.

[0011] Furthermore, the diameter of the base circle is 0.5–3 mm, the diameter of the power rod is 0.3–1.5 mm, the diameter of the support rod is 0.1–1 mm, and the spacing between the support rods is 0.5–3 mm.

[0012] Furthermore, the diameter of the directional salt precipitation structure is 5-10 mm, and the diameter of its internal pores is 0.01-0.5 mm.

[0013] Furthermore, the photothermal conversion coating is an inorganic coating or an organic coating. The raw materials of the inorganic coating include, but are not limited to, gold, silver, copper, and platinum. The materials of the organic coating include, but are not limited to, hydrophilic carbon powder, hydrophilic carbon nanotubes, a composite of hydrophilic graphene and acrylic resin, or dopamine.

[0014] On the other hand, the present invention provides a method for manufacturing a solar evaporator based on 3D printing, characterized in that the method for manufacturing the solar evaporator for brine separation as described above includes the following steps:

[0015] A 3D modeling software was used to create the overall geometric model of the solar evaporator.

[0016] The structural framework of the overall geometric model was constructed using 3D printing technology, and impurities on the surface of the structural framework were removed using a plasma cleaner to enhance its adhesion to the subsequently applied photothermal conversion coating.

[0017] A photothermal conversion coating is applied to the surface of the structural frame, and the surface is cleaned using a plasma cleaner to enhance its hydrophilicity.

[0018] Furthermore, the present invention provides a method for manufacturing a solar evaporator based on 3D printing, characterized in that the method for manufacturing the solar evaporator for brine separation as described above includes the following steps:

[0019] Geometric models of open microchannels, water storage and salt collection structures, and directional salt precipitation structures were established using 3D modeling software.

[0020] The open microchannel, water-collecting and salt-collecting structure, and directional salt-precipitating structure were constructed using 3D printing technology, and impurities on the surface of each structural framework were removed using a plasma cleaner to enhance their adhesion to the subsequently coated photothermal conversion coating.

[0021] A photothermal conversion coating is applied to the surface of the open microchannel, the water-collecting and salt-forming structure, and the directional salt-forming structure. The surface of the open microchannel, the water-collecting and salt-forming structure, and the directional salt-forming structure is then cleaned using a plasma cleaner to enhance their hydrophilicity.

[0022] The open microchannel, water storage and salt collection structure, and directional salt release structure are assembled sequentially from bottom to top.

[0023] Furthermore, the 3D printing technology includes, but is not limited to, resin-based 3D printing, ceramic-based 3D printing, metal 3D printing, and photopolymerization 3D printing.

[0024] Furthermore, the photothermal conversion coating is an inorganic coating or an organic coating. The raw materials of the inorganic coating include, but are not limited to, gold, silver, copper, and platinum, and its preparation methods include, but are not limited to, magnetron sputtering and electroless plating. The materials of the organic coating include hydrophilic carbon powder or hydrophilic carbon nanotubes or a composite of hydrophilic graphene and acrylic resin or dopamine, and its preparation methods include, but are not limited to, chemical deposition.

[0025] Furthermore, the method for assembling the open microchannel, the water-collecting and salt-gathering structure, and the directional salt-gathering structure involves using adhesive to bond and assemble the various structures.

[0026] Compared with the prior art, the present invention has the following technical effects:

[0027] (1) The liquid in each component of the evaporator of the present invention can come into contact with the outside world, and can effectively utilize light, heat and other factors, thereby effectively improving the evaporation efficiency.

[0028] (2) The water storage and salt collection structure involved in the evaporator of the present invention can recover salt scale while temporarily storing water.

[0029] (3) The directional salt precipitation structure involved in the evaporator of the present invention can effectively precipitate salt in a directional manner, and the salt can spontaneously detach under the action of gravity after growing to a certain size.

[0030] (4) The evaporator of the present invention can be made using 3D printing technology, which has the advantages of fast molding speed, high processing accuracy and low manufacturing cost; it is cleaned by plasma cleaning machine, and hydrophilic groups such as -COOH, -OH are introduced to enhance the bonding force between the structural framework and the coated photothermal conversion coating on the one hand, and enhance the hydrophilicity on the other hand. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of a solar evaporator in one embodiment of the present invention;

[0032] Figure 2This is a three-dimensional structural diagram of an open microchannel in one embodiment of the present invention;

[0033] Figure 3 This is a top view of the open microchannel structure in one embodiment of the present invention;

[0034] Figure 4 This is a schematic cross-sectional view of a water storage and salt collection structure in one embodiment of the present invention;

[0035] Figure 5 This is a top view schematic diagram of the water storage and salt collection structure in one embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram of the directional salt precipitation structure in one embodiment of the present invention;

[0037] Figure 7 This is a flowchart illustrating the fabrication of a solar evaporator in one embodiment of the present invention. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but these are not intended to limit the scope of the invention.

[0039] Furthermore, the execution order of actions, steps, etc. in the apparatus and methods shown in the claims, specification, and drawings can be implemented in any order, unless a specific order is explicitly specified, and as long as the output of the preceding processing is not used in the subsequent processing.

[0040] See Figures 1 to 6 This invention provides a solar evaporator for brine separation, comprising, from bottom to top, an open microchannel 1, a water-collecting and salt-retaining structure 2, and a directional salt-separating structure 3. The surfaces of the open microchannel 1, the water-collecting and salt-retaining structure 2, and the directional salt-separating structure 3 are all coated with a photothermal conversion coating.

[0041] The open microchannel 1 has a porous structure, which allows for the drainage and evaporation of saline solution through capillary channels and a hydrophilic photothermal conversion coating. The porous design also ensures sufficient evaporation during liquid transport.

[0042] See Figure 3 and Figure 4 The central part of the water-collecting and salt-collecting structure 2 is the water-collecting section 21, and the outer part is the salt-collecting section 22; the water-collecting section 21 and the salt-collecting section 22 are separated by a baffle 23. The water-collecting section is used to temporarily store the liquid transported from the open microchannel, while the salt-collecting section is mainly used to collect the salt that falls off from the directional salt-collecting structure. The specific dimensions of the water-collecting section 21 and the salt-collecting section 22 can be determined according to the actual water treatment requirements.

[0043] See Figure 1 and Figure 5The directional salt precipitation structure 3 is a porous cylindrical structure that is inclined from the water collection part 21 to the upper part of the salt collection part 22. It can transport the substance out and perform water evaporation and salt crystallization in real time.

[0044] When using the solar evaporator, the salt water flows upward through the open microchannel 1 containing capillary channels and a hydrophilic coating, reaching the water collection section 21 of the water storage and salt collection structure 2. Then, the salt is effectively precipitated in a directional manner through the directional salt precipitation structure 3. After the salt grows to a certain size, it can fall off under the action of gravity and fall into the salt collection section 22 of the water storage and salt collection structure 2, thus achieving the purpose of separating the salt water.

[0045] For a better technical solution, see [link to relevant documentation]. Figure 2 and Figure 3 The open microchannel 1 is a porous structure composed of multiple power rods 11 and support rods 12. The power rods 11 are evenly distributed on a base circle 10, and the support rods 12 connect the power rods 11 to avoid deformation caused by excessive length of the power rods. The power rods 11 have a capillary structure and a hydrophilic photothermal conversion coating, which provides power for the water to rise and continuously evaporates water while transporting it, thereby improving the evaporation rate of the device.

[0046] As a better technical solution, the diameter of the base circle is 0.5-3mm, the diameter of the power rod 11 is 0.3-1.5mm, and the specific size can be determined according to the size of the base circle; the diameter of the support rod 12 is 0.1-1mm, and the spacing of the support rods 12 is 0.5-3mm, and the specific diameter and spacing can be determined according to the size of the base circle and actual production needs.

[0047] The dimensions of the directional salt-gathering structure and its pores can be adjusted according to actual conditions, and the diameter of the pores used for filling should be smaller than the diameter of the directional salt-gathering structure. Preferably, the diameter of the directional salt-gathering structure 3 is 5-10 mm, depending on the size of the water storage and salt collection area and actual production needs, ensuring a higher yield while ensuring proper placement; the diameter of its internal pores is 0.01-0.5 mm, which can ensure a larger water supply rate and rising height, guaranteeing efficient and continuous water and salt production.

[0048] As an example, the photothermal conversion coating can be an inorganic or organic coating; the raw materials for the inorganic coating include, but are not limited to, gold, silver, copper, and platinum; the materials for the organic coating include, but are not limited to, hydrophilic toner, hydrophilic carbon nanotubes, a composite of hydrophilic graphene and acrylic resin, or dopamine. Here, the particle size of the toner is larger than that of the carbon nanotubes, and the particle size of the carbon nanotubes is larger than that of the graphene.

[0049] See Figure 7 The aforementioned solar evaporator is manufactured using 3D printing technology, specifically including the following steps:

[0050] S1. Use 3D modeling software to establish the overall geometric model of the solar evaporator or establish the geometric models of the open microchannel 1, the water storage and salt collection structure 2, and the directional salt precipitation structure 3 respectively.

[0051] S2. Using 3D printing technology, construct the overall or separate structural framework of the open microchannel 1, water storage and salt collection structure 2, and directional salt precipitation structure 3, and use a plasma cleaner to remove impurities from the surface of the structural framework to enhance its bonding force with the photothermal conversion coating applied afterward.

[0052] S3. Apply a photothermal conversion coating to the surface of the open microchannel 1, the water-collecting and salt-forming structure 2, and the directional salt-forming structure 3, and use a plasma cleaner to clean the surface of the open microchannel, the water-collecting and salt-forming structure, and the directional salt-forming structure to enhance their hydrophilicity.

[0053] For the separately constructed structural frameworks, the open microchannel 1, the water-collecting and salt-gathering structure 2, and the directional salt-gathering structure 3 are assembled sequentially from bottom to top. As an example, they are assembled by using glue to bond the various structures together.

[0054] As an example, the 3D printing technology in S2 includes, but is not limited to, resin-based 3D printing, ceramic-based 3D printing, metal 3D printing, and photopolymerization 3D printing, among which the method of using high-precision photopolymerization 3D printing to construct the structure is optimal.

[0055] The preparation methods of the photothermal conversion coating in S3 include, but are not limited to, chemical deposition, magnetron sputtering, and chemical plating.

[0056] The technical solution of the present invention will be described more clearly below through several specific embodiments.

[0057] Example 1

[0058] The geometric model of this invention was established using 3D modeling software. Next, the framework of the geometric model was constructed using a 3D printer, with acrylic resin as the raw material. Then, a plasma cleaner (using air) was used to remove impurities from the surface of the structural framework to enhance the adhesion of the photothermal conversion coating. Following this, a hydrophilic coating solution was prepared by mixing hydrophilic toner, acrylic resin, anhydrous ethanol, and a surfactant together and stirring thoroughly. The multi-scale structural framework, after being cleaned by the plasma cleaner, was then placed in the aforementioned hydrophilic coating solution for 6 hours, and then removed, where a photothermal conversion coating was chemically deposited. Finally, it was dried in an oven, and its surface was cleaned again using a plasma cleaner (using air) to enhance its hydrophilicity. The solar evaporator that simultaneously achieves salt collection and water evaporation, as described in this application, was thus fabricated.

[0059] Example 2

[0060] The geometric model of this invention was established using 3D modeling software. Next, the framework of the geometric model was constructed using a 3D printer, with acrylic resin as the raw material. Then, a plasma cleaner (using air) was used to remove impurities from the surface of the structural framework to enhance the adhesion of the photothermal conversion coating. Following this, a hydrophilic coating solution was prepared by mixing hydrophilic carbon nanotubes, acrylic resin, anhydrous ethanol, and a surfactant together and stirring thoroughly. The plasma-cleaned structural framework was then placed in the aforementioned hydrophilic coating solution for 6 hours, and then removed. Finally, it was dried in an oven, and its surface was cleaned again using a plasma cleaner (using air) to enhance its hydrophilicity. The solar evaporator that simultaneously achieves salt collection and water evaporation, as described in this application, was thus fabricated.

[0061] Example 3

[0062] Geometric models of the open microchannel, water-collecting and salt-forming structure, and directional salt-forming structure of this invention were established using 3D modeling software. Next, the open microchannel, water-collecting and salt-forming structure, and directional salt-forming structure were constructed using a 3D printer, with acrylic resin as the raw material. Then, a plasma cleaner (using air) was used to remove impurities from the surface of the structural framework to enhance the adhesion of the photothermal conversion coating. Following this, a pure gold coating was applied to the surface of the open microchannel, water-collecting and salt-forming structure, and directional salt-forming structure using magnetron sputtering. Finally, the surfaces of the open microchannel, water-collecting and salt-forming structure were cleaned using a plasma cleaner (using air) to remove surface impurities and enhance their hydrophilicity. Finally, a strong adhesive was used to... Figure 1 The adhesive is pasted at the indicated position, and after the adhesive cures, the solar evaporator that simultaneously collects salt and evaporates water, as described in this application, is manufactured.

[0063] Example 4

[0064] Geometric models of the open microchannel, water-collecting and salt-forming structure, and directional salt-forming structure of this invention were established using 3D modeling software. Next, the open microchannel, water-collecting and salt-forming structure, and directional salt-forming structure were constructed using a 3D printer, with polylactic acid resin as the raw material. Then, a plasma cleaner (using air) was used to remove impurities from the surface of the structural frame to enhance the adhesion of the photothermal conversion coating. Following this, a pure copper coating was applied to the surface of the open microchannel, water-collecting and salt-forming structure, and directional salt-forming structure using chemical plating. Finally, the surfaces of the open microchannel, water-collecting and salt-forming structure, and directional salt-forming structure were cleaned using a plasma cleaner (using air) to remove surface impurities and enhance their hydrophilicity. Finally, a strong adhesive was used to... Figure 1The adhesive is pasted at the indicated position, and after the adhesive cures, the solar evaporator that simultaneously collects salt and evaporates water, as described in this application, is manufactured.

[0065] Example 5

[0066] The geometric model of this invention was established using 3D modeling software. Next, the framework of the geometric model was constructed using a 3D printer, with ceramic as the raw material. Then, a plasma cleaner (using oxygen) was used to remove impurities from the surface of the structural framework to enhance the adhesion of the photothermal conversion coating. Following this, a hydrophilic coating solution was prepared by mixing dopamine, deionized water, and a surfactant together and stirring thoroughly. The structure, after being cleaned by the plasma cleaner, was then placed in the aforementioned hydrophilic coating solution for 6 hours, and then removed, where a photothermal conversion coating was chemically deposited. Finally, it was dried in an oven, and its surface was cleaned again using a plasma cleaner (using oxygen) to enhance its hydrophilicity. The solar evaporator that simultaneously achieves salt collection and water evaporation, as described in this application, was thus fabricated.

[0067] Example 6

[0068] The geometric model of this invention was established using 3D modeling software. Next, the framework of the geometric model was constructed using a 3D printer, with aluminum as the raw material. Then, a plasma cleaner (using oxygen) was used to remove impurities from the surface of the structural framework to enhance the adhesion of the photothermal conversion coating. Following this, a layer of silver was sprayed onto the surface of the 3D-printed structure using magnetron sputtering. Finally, the surface was cleaned using a plasma cleaner (using oxygen) to enhance its hydrophilicity. The solar evaporator that simultaneously achieves salt collection and water evaporation, as described in this application, was thus fabricated.

[0069] Example 7

[0070] The geometric model of this invention was established using 3D modeling software. Next, the framework of the geometric model was constructed using a 3D printer, with photocurable resin as the raw material. Then, a plasma cleaner (using oxygen) was used to remove impurities from the surface of the structural framework to enhance the adhesion of the photothermal conversion coating. Following this, a layer of platinum was sprayed onto the surface of the 3D-printed structure using magnetron sputtering. Finally, the surface was cleaned using a plasma cleaner (using oxygen) to enhance its hydrophilicity. The solar evaporator that simultaneously achieves salt collection and water evaporation, as described in this application, was thus fabricated.

[0071] In summary, this invention provides a solar evaporator for brine separation and its 3D printing-based fabrication method. The solar evaporator utilizes 3D printing and plasma cleaning technologies to achieve salt collection and water evaporation. The solar evaporator, from bottom to top, includes an open microchannel with a photothermal conversion coating on both surfaces, a water-collecting and salt-retaining structure, and a directional salt-precipitating structure. The open microchannel has a porous structure, guiding and evaporating brine through capillary channels and a hydrophilic coating. The central part of the water-collecting and salt-retaining structure is a water collection section, and the outer part is a salt collection section. The water collection section and the salt collection section are separated by a baffle. The directional salt-precipitating structure is located at the outer edge of the water collection section and is a cylindrical structure filled with a porous structure. In this invention, the liquid within each component of the evaporator can contact the outside environment, effectively utilizing light and heat, significantly improving evaporation efficiency, and recovering salt scale while temporarily storing water.

[0072] Those skilled in the art should understand that variations can be implemented by combining existing technology with the above embodiments, which will not be elaborated here. Such variations do not affect the essence of the present invention, and will not be elaborated here either.

[0073] The preferred embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and the devices and structures not described in detail should be understood as being implemented in a conventional manner in the art. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. This does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's technical solutions still fall within the protection scope of the present invention.

Claims

1. A solar evaporator for brine separation, characterized in that, From bottom to top, it includes an open microchannel (1), a water-collecting and salt-gathering structure (2), and a directional salt-gathering structure (3); the surfaces of the open microchannel (1), the water-collecting and salt-gathering structure (2), and the directional salt-gathering structure (3) are all coated with a photothermal conversion coating. The open microchannel (1) has a porous structure, which guides and evaporates salt water through capillary channels and a hydrophilic photothermal conversion coating; the open microchannel (1) is a porous structure composed of multiple power rods (11) and support rods (12); the power rods (11) are evenly distributed on a base circle (10), and the support rods (12) connect the power rods (11); The central part of the water storage and salt collection structure (2) is the water collection part (21), and the outer part is the salt collection part (22); the water collection part (21) and the salt collection part (22) are separated by a baffle (23); The directional salt precipitation structure (3) is a cylindrical structure filled with a porous structure, used for water evaporation and salt crystallization, and is inclined from the water collection part (21) to the upper part of the salt collection part (22). The manufacturing process of the solar evaporator is as follows: The overall geometric model of the solar evaporator was established using 3D modeling software; the structural framework of the overall geometric model was constructed using 3D printing technology; and impurities on the surface of the structural framework were removed using a plasma cleaner to enhance its adhesion to the subsequently applied photothermal conversion coating. A photothermal conversion coating is applied to the surface of the structural frame, and the surface is cleaned using a plasma cleaner to enhance its hydrophilicity. or, Geometric models of the open microchannel (1), water-collecting and salt-forming structure (2), and directional salt-forming structure (3) were established using 3D modeling software. The open microchannel (1), water-collecting and salt-forming structure (2), and directional salt-forming structure (3) were constructed using 3D printing technology. Impurities on the surface of each structural frame were removed using a plasma cleaner to enhance their bonding with the photothermal conversion coating applied later. A photothermal conversion coating was applied to the surface of the open microchannel (1), water-collecting and salt-forming structure (2), and directional salt-forming structure (3). The surface of the open microchannel (1), water-collecting and salt-forming structure (2), and directional salt-forming structure (3) was cleaned using a plasma cleaner to enhance their hydrophilicity. The open microchannel (1), water-collecting and salt-forming structure (2), and directional salt-forming structure (3) were assembled sequentially from bottom to top.

2. The solar evaporator for brine separation according to claim 1, characterized in that, The diameter of the base circle (10) is 0.5~3mm, the diameter of the power rod (11) is 0.3~1.5mm, the diameter of the support rod (12) is 0.1~1mm, and the spacing of the support rods (12) is 0.5~3mm.

3. A solar evaporator for brine separation according to claim 2, characterized in that, The diameter of the directional salt precipitation structure (3) is 5~10 mm, and the diameter of its internal pores is 0.01~0.5 mm.

4. A solar evaporator for brine separation according to claim 1, characterized in that, The photothermal conversion coating is an inorganic coating or an organic coating. The raw materials for the inorganic coating include gold, silver, copper, and platinum. The materials for the organic coating include hydrophilic carbon powder, hydrophilic carbon nanotubes, a composite of hydrophilic graphene and acrylic resin, or dopamine.

5. A solar evaporator according to claim 1, characterized in that, The 3D printing technologies include resin-based 3D printing, ceramic-based 3D printing, metal 3D printing, and photopolymerization 3D printing.

6. A solar evaporator according to claim 1, characterized in that, The photothermal conversion coating is an inorganic coating or an organic coating. The raw materials for the inorganic coating include gold, silver, copper, and platinum, and its preparation method includes magnetron sputtering and chemical plating. The materials for the organic coating include hydrophilic carbon powder, hydrophilic carbon nanotubes, a composite of hydrophilic graphene and acrylic resin, or dopamine, and its preparation method includes chemical deposition.

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