A photothermal evaporation body, a preparation method therefor and applications thereof

Abstract

The application provides a photothermal evaporation body and a preparation method and application thereof, and belongs to the technical field of brine treatment. The application provides a photothermal evaporation body, which comprises a hydrophilic mass transfer bottom layer, the hydrophilic mass transfer bottom layer comprises a vertical part and two branches arranged at the top end of the vertical part, the hydrophilic mass transfer bottom layer penetrates a floating structure, and a hydrophobic light absorption layer is arranged on the upper surfaces of the two branches. The application constructs a photothermal evaporation body with an adjustable brine transmission path, can efficiently dredge salt crystals to a non-light absorption area of the material, achieves a high-efficiency and stable concentrated brine treatment effect, through the design of the interface structure of the photothermal evaporation body, the accumulated salt at the interface is dredged, interface salt pollution that may be formed is converted into recoverable edge salt crystals, high-salinity wastewater can be efficiently treated for a long time, zero liquid discharge of high-salinity wastewater is realized, the shortcomings of high energy consumption and high ecological cost of traditional technologies are broken through, and support is provided for green and low-carbon treatment of high-salinity wastewater.

Description

Technical Field

[0001] This invention relates to the field of brine treatment technology, and in particular to a photothermal evaporator, its preparation method, and its application. Background Technology

[0002] Traditional photothermal evaporation technology struggles to handle high-salinity brine. During continuous photothermal treatment of high-salinity brine, the salt concentration steadily increases, eventually saturating and depositing on the surface and inside the evaporator, forming salt contamination. These white salt particles affect light absorption, vapor dissipation, and water supply. Related technologies have disclosed solutions to salt contamination by constructing hydrophobic surfaces to prevent brine migration to the evaporator surface. However, long-term operational stability remains poor; that is, as photothermal evaporation continues, salt accumulation increases, exceeding the surface tension limit and still resulting in salt contamination, thus reducing photothermal evaporation efficiency. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a photothermal evaporator, its preparation method, and its application. The photothermal evaporator of this invention can efficiently guide salt crystallization to the non-light-absorbing region, achieving a highly efficient and stable concentrated brine treatment effect.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides a photothermal evaporator, comprising:

[0006] A hydrophilic mass transfer substrate, comprising a vertical portion and two branches located at the top of the vertical portion, wherein the hydrophilic mass transfer substrate penetrates the floating structure;

[0007] A hydrophobic light-absorbing layer is disposed on the upper surface of the two branches.

[0008] Preferably, the two branches have the same angle with the horizontal plane.

[0009] Preferably, the angle between the two branches and the horizontal plane is 0 to 75°.

[0010] Preferably, the hydrophilic mass transfer substrate is made of melamine foam coated with graphene oxide-polyethyleneimine.

[0011] Preferably, the hydrophobic light-absorbing layer is made of polydimethylsiloxane.

[0012] Preferably, the two branches of the hydrophilic mass transfer layer have the same thickness, and the thickness ratio of the two branches to the hydrophobic light-absorbing layer is 1:0.01 to 1.

[0013] Preferably, the floating structure is a hydrophobic foam.

[0014] The present invention also provides a method for preparing the photothermal evaporator described in the above technical solution, comprising the following steps:

[0015] The hydrophobic light-absorbing layer is deposited on the surface of the hydrophilic mass transfer substrate to form the hydrophobic light-absorbing layer, which is then combined with the floating structure to obtain the photothermal evaporator.

[0016] The present invention also provides the application of the photothermal evaporator described in the above technical solution or the photothermal evaporator prepared by the preparation method described in the above technical solution in brine treatment.

[0017] Preferably, the salt concentration in the brine to be treated during the brine treatment is 0-15 wt%, and not 0.

[0018] The present invention provides a photothermal evaporator, comprising: a hydrophilic mass transfer substrate, the hydrophilic mass transfer substrate including a vertical portion and two branches disposed at the top of the vertical portion, the hydrophilic mass transfer substrate penetrating a floating structure; and a hydrophobic light-absorbing layer disposed on the upper surface of the two branches.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] This invention constructs a photothermal evaporator with an adjustable brine transport path, which can efficiently guide salt crystallization to the non-light-absorbing region of the material, achieving a highly efficient and stable concentrated brine treatment effect. The principle is as follows: Under sunlight, water molecules in the brine can be directionally concentrated in the photothermal evaporator (directional concentration is due to the hydrophilic effect of the hydrophilic mass transfer layer; under capillary action, water will migrate from the bottom to the top). Water vapor continuously escapes upwards, while the lower solution can be concentrated step by step. The photothermal evaporator of this invention has smaller bends, which is more conducive to salt dispersion and more conducive to achieving salt resistance. By adjusting the angle of the two branches of the photothermal evaporator, the water supply flow rate can be controlled, the salt concentration rate can be effectively regulated, and the saturation concentration can be precisely limited to the edge of the material, achieving simultaneous and efficient recovery of water vapor and salt resources. That is, by designing the interface structure of the photothermal evaporator, the salt accumulated at the interface can be channeled, and the potential interface salt pollution can be transformed into recyclable edge salt crystals. This invention can treat high-salt wastewater efficiently for a long time, achieving zero liquid discharge of high-salt wastewater. It overcomes the shortcomings of traditional technologies such as high energy consumption and high ecological costs, and provides support for the green and low-carbon treatment of high-salt wastewater.

[0021] The present invention also provides the application of the photothermal evaporator described in the above technical solution in brine treatment, which can be used to treat high salinity brine (the salt concentration in the brine is 0-15 wt%, and not 0). Attached Figure Description

[0022] Figure 1This is a schematic diagram of the principle of photothermal evaporator for treating brine in this invention. In the diagram, 1 is the hydrophobic light-absorbing layer, 2 is the hydrophilic mass transfer bottom layer, 3 is the floating structure, and 4 is the brine.

[0023] Figure 2 The evaporation rate curve of brine treated by the photothermal evaporator in Comparative Example 1 is shown.

[0024] Figure 3 The evaporation rate curve of brine treated by the photothermal evaporator in Example 1;

[0025] Figure 4 The evaporation rate curve of brine treated by the photothermal evaporator in Example 2;

[0026] Figure 5 The evaporation rate curve of brine treated by the photothermal evaporator in Example 3;

[0027] Figure 6 The evaporation rate curve of brine treated by the photothermal evaporator in Example 4 is shown. Detailed Implementation

[0028] This invention provides a photothermal evaporator, comprising:

[0029] A hydrophilic mass transfer substrate, comprising a vertical portion and two branches located at the top of the vertical portion, wherein the hydrophilic mass transfer substrate penetrates the floating structure;

[0030] A hydrophobic light-absorbing layer is disposed on the upper surface of the two branches.

[0031] In this invention, the angles between the two branches and the horizontal plane are preferably the same; if the angles of the two branches are different, the balance will be lost, so it is preferable to add a load to balance the two branches.

[0032] In this invention, the angle between the two branches and the horizontal plane is preferably 0° to 75°, specifically 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, or 75°. When the angle between the two branches and the horizontal plane is 0°, the hydrophilic mass transfer layer has a T-shaped structure; when the angle between the two branches and the horizontal plane is not 0°, the hydrophilic mass transfer layer has a Y-shaped structure. Taking the Y-shaped structure as an example, the principle of the photothermal evaporator for treating brine provided by this invention is as follows: Figure 1As shown in the figure, 1 is the hydrophobic light-absorbing layer, 2 is the hydrophilic mass transfer layer, 3 is the floating structure, and 4 is the salt water. Under the drive of sunlight, the water molecules in the salt water 4 can be directionally concentrated in the photothermal evaporator (the directional concentration is due to the hydrophilic effect of the hydrophilic mass transfer layer 2; under the action of capillary force, water will migrate from the bottom to the top). Water vapor continuously escapes upwards, while the lower solution salt water 4 can be concentrated step by step, efficiently guiding salt crystallization to the non-light-absorbing region of the photothermal evaporator (the edge part of the photothermal evaporator). By adjusting the angle of the Y-shaped structure of the photothermal evaporator, the water supply flow rate can be controlled. Light is absorbed by the surface of the hydrophobic light-absorbing layer 1 in the direction of the arrow and converted into heat. Water vapor undergoes a phase change under the drive of the photothermal reaction. The arrow inside the hydrophilic mass transfer layer 2 indicates the direction of water directional transport.

[0033] In this invention, the hydrophilic mass transfer substrate is preferably made of melamine foam coated with graphene oxide-polyethyleneimine.

[0034] In this invention, the graphene oxide-polyethyleneimine-coated melamine foam is preferably prepared by a method comprising the following steps:

[0035] Graphene oxide (GO) is treated with alkali to obtain alkaline graphene oxide.

[0036] The alkaline graphene oxide and polyethyleneimine are covalently crosslinked to obtain graphene oxide-polyethyleneimine.

[0037] Melamine foam coated with graphene oxide-polyethyleneimine is obtained by impregnating, extruding, and pulling the graphene oxide-polyethyleneimine.

[0038] This invention involves treating graphene oxide with an alkali to obtain alkaline graphene oxide.

[0039] In this invention, the alkaline reagent used for the alkaline treatment is preferably an aqueous solution of inorganic hydroxide, which is preferably an aqueous solution of NaOH, and the concentration of the NaOH aqueous solution is preferably 1 mol / L.

[0040] In this invention, the graphene oxide is preferably used in the form of a graphene oxide dispersion, and the volume ratio of the graphene oxide to the NaOH aqueous solution is preferably 50:4.5.

[0041] After obtaining alkaline graphene oxide, the present invention covalently crosslinks the alkaline graphene oxide with polyethyleneimine to obtain graphene oxide-polyethyleneimine.

[0042] In this invention, the mass ratio of alkaline graphene oxide to polyethyleneimine is preferably 3:1 to 1:3.

[0043] In this invention, the temperature for covalent crosslinking is preferably room temperature, and the time is preferably 0.5 to 3 hours. The principle of covalent crosslinking is that the COO- at the end of graphene oxide reacts with the NH2 at the end of polyethyleneimine to form amide bonds.

[0044] In this invention, it is preferable that no other substances are added during the covalent crosslinking.

[0045] In this invention, the covalent crosslinking is preferably performed under ultrasound.

[0046] After obtaining graphene oxide-polyethyleneimine, the present invention impregnates, extrudes, and pulls melamine foam with the graphene oxide-polyethyleneimine to obtain melamine foam coated with the graphene oxide-polyethyleneimine.

[0047] In this invention, the melamine foam is preferably purchased from Shanghai Beiyou Building Materials Co., Ltd., and the product model is melamine nano cotton.

[0048] In this invention, the impregnation is performed every 16cm 2 It is preferable to absorb 20-24 mL of liquid on the melamine foam.

[0049] In this invention, the lifting process preferably includes heat treatment, the purpose of which is to improve the stability of the hydrophilic mass transfer substrate.

[0050] In this invention, the heat treatment temperature is preferably 50–150°C, specifically 50, 80, 100, 120, or 150°C, and the time is preferably 8–15 hours. ， Specifically, it can be 8, 10, 12, or 15 hours.

[0051] In this invention, the hydrophobic light-absorbing layer is preferably made of polydimethylsiloxane (PDMS).

[0052] In this invention, the thickness of the two branches of the hydrophilic mass transfer layer is preferably the same, and the thickness ratio of the two branches to the hydrophobic light-absorbing layer is preferably 1:0.01 to 1, specifically 1:0.01, 1:0.05, 1:0.1, 1:0.5 or 1:1.

[0053] In this invention, the thickness of the two branches is preferably 1 cm.

[0054] In this invention, the thickness of the hydrophobic light-absorbing layer is preferably 0.01 to 1 cm, specifically 0.01, 0.1, 0.5 or 1 cm.

[0055] In this invention, the thickness of the vertical portion of the hydrophilic mass transfer substrate is preferably 1 cm.

[0056] In this invention, the floating structure is preferably a hydrophobic foam, and the hydrophobic foam is preferably polystyrene foam. This invention does not impose any special limitations on the specific dimensional parameters of the floating structure; parameters well-known to those skilled in the art can be used.

[0057] The present invention also provides a method for preparing the photothermal evaporator described in the above technical solution, comprising the following steps:

[0058] The hydrophobic light-absorbing layer is deposited on the surface of the hydrophilic mass transfer substrate to form the hydrophobic light-absorbing layer, which is then combined with the floating structure to obtain the photothermal evaporator.

[0059] The present invention does not impose any particular limitation on the specific method of deposition and combination, and any method known to those skilled in the art can be used.

[0060] The present invention also provides the application of the photothermal evaporator described in the above technical solution or the photothermal evaporator prepared by the preparation method described in the above technical solution in brine treatment.

[0061] In this invention, the salt concentration in the brine to be treated during the brine treatment is preferably 0 to 15 wt%, and not 0.

[0062] In this invention, the salt in the brine to be treated preferably includes one or more of sodium ions, potassium ions, calcium ions, magnesium ions, and chloride ions.

[0063] In this invention, the brine treatment is preferably carried out under illumination, and the intensity of the illumination is preferably 0.5–1.5 kW·m. -2 Specifically, it can be 0.5, 1, or 1.5 kW·m -2 .

[0064] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0065] The structure of the photothermal evaporator in the embodiments of the present invention is as follows: Figure 1 As shown.

[0066] Comparative Example 1

[0067] Preparation of graphene oxide-polyethyleneimine-coated melamine foam:

[0068] 1) Alkali treatment of graphene oxide: Adjust with 1M NaOH aqueous solution. The raw material ratio in the process is 50mL GO and 4.5mL NaOH aqueous solution.

[0069] 2) Covalent crosslinking of alkaline graphene oxide and polyethyleneimine: Alkaline graphene oxide and polyethyleneimine are mixed and covalently crosslinked to obtain graphene oxide-polyethyleneimine. The mass ratio of alkaline graphene oxide to polyethyleneimine is 1:3. The temperature is room temperature and the time is 3h.

[0070] 3) Impregnation-Extrusion-Lifting: Melamine foam (purchased from Shanghai Beiyou Building Materials Co., Ltd.) is thoroughly impregnated in a graphene oxide / polyethyleneimine solution. After impregnation, each 16cm section... 2 Melamine foam absorbs 24 mL of liquid.

[0071] 4) Heat treatment: The heat treatment temperature is 90℃ and the time is 12h to obtain melamine foam coated with graphene oxide-polyethyleneimine.

[0072] Preparation of a linear photothermal evaporator: Polydimethylsiloxane (PDMS) (0.01 cm thick) is deposited on the surface of melamine foam (1 cm thick) coated with graphene oxide-polyethyleneimine to obtain a hydrophobic graphene oxide-polyethyleneimine melamine foam. Then, it is combined with polystyrene foam (the polystyrene foam is used to make the hydrophobic graphene oxide-polyethyleneimine melamine foam float, and the surface of the polystyrene foam is wrapped with non-woven fabric, which is used to absorb water) to obtain the photothermal evaporator.

[0073] Simulated salt water (salinity 15 wt%) was treated using a photothermal evaporator under a light intensity of 1 kW·m². -2 Evaporation rate tests were conducted under the specified conditions. Figure 2 Table 1 shows the evaporation rate curve of brine treated by the photothermal evaporator in Comparative Example 1, and the data on the change of purified water produced by photothermal treatment over time.

[0074] Table 1. Data on the variation of purified water produced by solar thermal energy in Comparative Example 1 over time.

[0075] 1 1.360 2 1.348 3 1.320 4 1.274 5 1.215 6 1.171 7 1.067 8 0.818 9 0.616 10 0.529 11 0.542 12 0.563

[0076] Example 1

[0077] The steps for preparing graphene oxide-polyethyleneimine-coated melamine foam are the same as those in Comparative Example 1, serving as a hydrophilic mass transfer substrate.

[0078] A T-shaped photothermal evaporator was prepared: a hydrophilic mass transfer substrate (1 cm thick) had a vertical part and two branches. The angle between the two branches of the hydrophilic mass transfer substrate and the horizontal plane was set to 0°. A hydrophobic light-absorbing layer PDMS (0.01 cm thick) was deposited on the inner surface of the two branches of the hydrophilic mass transfer substrate. Then, it was combined with polystyrene foam to obtain the photothermal evaporator.

[0079] The simulated brine (salinity 15 wt%) was treated using the prepared photothermal evaporator under a light intensity of 1 kW·m. -2 Evaporation rate tests were conducted under the specified conditions. Figure 3 Table 2 shows the evaporation rate curve of the photothermal evaporator used to treat brine in Example 1, and the data on the change of photothermal purified water over time.

[0080] Table 2. Data on the variation of purified water produced by photothermal energy in Example 1 over time.

[0081] 1 0.987 2 1.051 3 1.071 4 1.066 5 1.065 6 1.074 7 1.088 8 1.083 9 1.071 10 1.065 11 1.055 12 1.038

[0082] Example 2

[0083] Similar to Example 1, the only difference is the preparation of a Y-shaped photothermal evaporator: the two branches of the hydrophilic mass transfer layer have an angle of 30° with the horizontal plane.

[0084] The simulated brine (salinity 15 wt%) was treated using the prepared photothermal evaporator under a light intensity of 1 kW·m. -2 Evaporation rate tests were conducted under the specified conditions. Figure 4 Table 3 shows the evaporation rate curve of the photothermal evaporator used to treat brine in Example 2, and the data on the change of photothermal purified water over time.

[0085] Table 3. Data on the variation of purified water produced by photothermal energy in Example 2 over time.

[0086] 1 1.206 2 1.195 3 1.199 4 1.184 5 1.169 6 1.141 7 1.115 8 1.100 9 1.091 10 1.084 11 1.075 12 1.062

[0087] Example 3

[0088] Similar to Example 1, the only difference is the preparation of a Y-shaped photothermal evaporator: the two branches of the hydrophilic mass transfer layer have an angle of 45° with the horizontal plane.

[0089] The simulated brine (salinity 15 wt%) was treated using the prepared photothermal evaporator under a light intensity of 1 kW·m. -2 Evaporation rate tests were conducted under the specified conditions. Figure 5 Table 4 shows the evaporation rate curve of the photothermal evaporator used to treat brine in Example 3, and the data on the change of photothermal purified water over time.

[0090] Table 4. Data on the variation of purified water produced by photothermal energy in Example 3 over time.

[0091] 1 1.255 2 1.262 3 1.267 4 1.213 5 1.152 6 1.137 7 1.141 8 1.138 9 1.128 10 1.097 11 1.069 12 1.048

[0092] Example 4

[0093] Similar to Example 1, the only difference is the preparation of a Y-shaped photothermal evaporator: the two branches of the hydrophilic mass transfer layer are at an angle of 60° to the horizontal plane.

[0094] The simulated brine (salinity 15 wt%) was treated using the prepared photothermal evaporator under a light intensity of 1 kW·m. -2 Evaporation rate tests were conducted under the specified conditions. Figure 6 Table 5 shows the evaporation rate curve of the photothermal evaporator used to treat brine in Example 4, and the data on the change of photothermal purified water over time.

[0095] Table 5. Data on the variation of purified water produced by solar thermal energy in Example 4 over time.

[0096] 1 1.701 2 1.738 3 1.682 4 1.717 5 1.755 6 1.723 7 1.706 8 1.671 9 1.633 10 1.596 11 1.578 12 1.514

[0097] contrast Figures 2-6 As shown in Tables 1-5, the central water supply method (Examples 1-4) can increase the stability of the material; as the tilt angle increases, the evaporation rate of the material gradually increases and can be maintained at 1.5 kg·m³. -2 ·h -1 This effectively reduces the damage of salt pollution to material performance and ensures the efficient and stable treatment performance of the photothermal evaporator for high-concentration brine.

[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A photothermal evaporator, characterized in that, include: A hydrophilic mass transfer substrate, specifically comprising a vertical portion and two branches located at the top of the vertical portion, wherein the hydrophilic mass transfer substrate penetrates the floating structure; A hydrophobic light-absorbing layer is disposed on the upper surface of the two branches; The two branches have the same angle with the horizontal plane, and the angle between the two branches and the horizontal plane is 60°. The hydrophilic mass transfer substrate has a Y-shaped structure; The hydrophilic mass transfer substrate is made of melamine foam coated with graphene oxide-polyethyleneimine. The thickness of both branches of the hydrophilic mass transfer substrate is 1 cm, and the thickness of the vertical part is 1 cm. The edge portion of the photothermal evaporator is provided with a non-light-absorbing area; The hydrophobic light-absorbing layer is made of polydimethylsiloxane and has a thickness of 0.01 cm.

2. The photothermal evaporator according to claim 1, characterized in that, The floating structure is a hydrophobic foam.

3. The method for preparing the photothermal evaporator according to claim 1 or 2, characterized in that, Includes the following steps: The hydrophobic light-absorbing layer is deposited on the surface of the hydrophilic mass transfer substrate to form the hydrophobic light-absorbing layer, which is then combined with the floating structure to obtain the photothermal evaporator.

4. The application of the photothermal evaporator according to claim 1 or 2 or the photothermal evaporator prepared by the preparation method according to claim 3 in brine treatment.

5. The application according to claim 4, characterized in that, During the brine treatment, the salt concentration in the brine to be treated is 0~15wt%, and is not 0.

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