Photo-thermal evaporation body and preparation method and application thereof

Abstract

The invention provides a photo-thermal evaporation body and a preparation method and application thereof, and belongs to the technical field of brine treatment. The invention provides a photo-thermal 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, and the hydrophilic mass transfer bottom layer penetrates through a floating structure; and the hydrophobic light absorption layer is arranged on the upper surfaces of the two branches. The photo-thermal evaporation body with an adjustable saline water transmission path is constructed, salt crystals can be efficiently dredged to a non-light-absorption area of a material, the efficient and stable strong saline water treatment effect is achieved, the interface structure of the photo-thermal evaporation body is designed, salt accumulated at the interface is dredged, and the strong saline water treatment effect is improved. Possible interface salt pollution is converted into recyclable edge salt crystals, high-salinity wastewater can be efficiently treated for a long time, zero liquid discharge of the high-salinity wastewater is realized, the defects of high energy consumption and high ecological cost in the traditional technology are overcome, and support is provided for green and low-carbon treatment of the high-salinity wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of brine treatment, and in particular to a photothermal evaporator and a preparation method and application thereof. Background Art

[0002] Traditional photothermal evaporation technology has difficulty in treating high-salinity brine. When photothermal high-salinity brine treatment is continued, the salt concentration will continue to rise and saturate until it is deposited on the surface and inside of the evaporator to form salt pollution. These white salt particles will affect light absorption, vapor escape and water supply. Related technologies disclose a way to solve the salt pollution problem by constructing a hydrophobic surface to hinder the migration of brine to the surface of the evaporator. However, the stability of long-term operation is still poor. That is, when photothermal evaporation continues, the amount of salt accumulation continues to increase, breaking through the limit that can be suppressed by surface tension, and still forming salt pollution, which weakens the efficiency of photothermal evaporation. Summary of the invention

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

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a photothermal evaporation body, comprising:

[0006] A hydrophilic mass transfer bottom layer, the hydrophilic mass transfer bottom layer comprising a vertical portion and two branches arranged at the top of the vertical portion, the hydrophilic mass transfer bottom layer passing through the floating structure;

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

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

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

[0010] Preferably, the material of the hydrophilic mass transfer bottom layer is 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 bottom layer have the same thickness, and the thickness ratio of the two branches to the hydrophobic light absorbing layer is 1:0.01-1.

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

[0014] The present invention also provides a method for preparing the photothermal evaporation body 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 bottom layer 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 use 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 salt water treatment.

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

[0018] The present invention provides a photothermal evaporator, comprising: a hydrophilic mass transfer bottom layer, the hydrophilic mass transfer bottom layer comprising a vertical part and two branches arranged at the top of the vertical part, the hydrophilic mass transfer bottom layer penetrates a floating structure; and a hydrophobic light absorbing layer arranged on the upper surfaces of the two branches.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention constructs a photothermal evaporator with an adjustable brine transmission path, which can efficiently guide salt crystals to the non-light-absorbing area of ​​the material to achieve an efficient and stable concentrated brine treatment effect. The principle is as follows: driven by 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 bottom layer. Under the action of capillary force, water will migrate from the bottom to the top), water vapor continuously escapes upward, and the lower layer solution can be concentrated step by step. The photothermal evaporator of the present invention has smaller corners, which is more conducive to the evacuation of salt and more conducive to achieving salt resistance. By adjusting the two branch angles 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 limited just at the edge of the material, thereby realizing the simultaneous and efficient recovery of water vapor and salt resources. That is, the present invention designs the interface structure of the photothermal evaporator, guides the salt accumulated at the interface, and converts the possible interface salt pollution into recoverable edge salt crystals. It can efficiently treat high-salt wastewater for a long time and achieve zero liquid discharge of high-salt wastewater, breaking through the shortcomings of high energy consumption and high ecological cost of traditional technologies, and providing support for the green and low-carbon treatment of high-salt wastewater.

[0021] The present invention also provides the use 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 0-15wt% and not 0). BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1The schematic diagram of the photothermal evaporator for treating salt water of the present invention is shown in FIG. 1, which is a hydrophobic light-absorbing layer, 2, which is a hydrophilic mass transfer bottom layer, 3, which is a floating structure, and 4, which is salt water;

[0023] Figure 2 This is the evaporation rate curve of the salt water treated by the photothermal evaporator of Comparative Example 1;

[0024] Figure 3 This is the evaporation rate curve of salt water treated by the photothermal evaporator in Example 1;

[0025] Figure 4 This is the evaporation rate curve of salt water treated by the photothermal evaporator of Example 2;

[0026] Figure 5 This is the evaporation rate curve of salt water treated by the photothermal evaporator of Example 3;

[0027] Figure 6 This is the evaporation rate curve of salt water treated by the photothermal evaporator of Example 4. DETAILED DESCRIPTION

[0028] The present invention provides a photothermal evaporation body, comprising:

[0029] A hydrophilic mass transfer bottom layer, the hydrophilic mass transfer bottom layer comprising a vertical portion and two branches arranged at the top of the vertical portion, the hydrophilic mass transfer bottom layer passing through the floating structure;

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

[0031] In the present invention, the angles between the two branches and the horizontal plane are preferably the same; when the angles of the two branches are different, the balance will be lost, and preferably, weights are added to balance the two branches.

[0032] In the present 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 bottom layer has a T-shaped structure; when the angle between the two branches and the horizontal plane is not 0°, the hydrophilic mass transfer bottom layer has a Y-shaped structure. Taking the Y-shaped structure as an example, the principle of treating salt water with the photothermal evaporator provided by the present invention is as follows: Figure 1As shown in the figure, 1 is a hydrophobic light-absorbing layer, 2 is a hydrophilic mass transfer bottom layer, 3 is a floating structure, and 4 is brine. Driven by sunlight, water molecules in the brine 4 can be directionally concentrated in the photothermal evaporator (directional concentration is due to the hydrophilic effect of the hydrophilic mass transfer bottom layer 2. Under the action of capillary force, water will migrate from the bottom to the top), and water vapor continuously escapes upward, while the lower solution brine 4 can be concentrated step by step, and the salt crystals are efficiently guided to the non-light-absorbing area of ​​the photothermal evaporator (the edge 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 arrow direction of the hydrophobic light-absorbing layer 1 and converted into heat. Water vapor undergoes a phase change driven by the photothermal reaction. The arrow inside the hydrophilic mass transfer bottom layer 2 indicates the direction of directional water transport.

[0033] In the present invention, the material of the hydrophilic mass transfer bottom layer is preferably melamine foam coated with graphene oxide-polyethyleneimine.

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

[0035] treating graphene oxide (GO) with alkali to obtain alkaline graphene oxide;

[0036] Covalently cross-linking the alkaline graphene oxide and polyethyleneimine to obtain graphene oxide-polyethyleneimine;

[0037] The melamine foam is impregnated, extruded and pulled by the graphene oxide-polyethyleneimine to obtain the melamine foam coated with the graphene oxide-polyethyleneimine.

[0038] The present invention performs alkali treatment on graphene oxide to obtain alkaline graphene oxide.

[0039] In the present invention, the alkaline agent used in the alkaline treatment is preferably an inorganic hydroxide aqueous solution, the inorganic hydroxide aqueous solution is preferably a NaOH aqueous solution, and the concentration of the NaOH aqueous solution is preferably 1 mol / L.

[0040] In the present 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 the alkaline graphene oxide, the present invention performs covalent cross-linking of the alkaline graphene oxide and polyethyleneimine to obtain graphene oxide-polyethyleneimine.

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

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

[0044] In the present invention, it is preferred that no other substances are added during the covalent cross-linking.

[0045] In the present invention, the covalent cross-linking is preferably performed under ultrasound.

[0046] After obtaining graphene oxide-polyethyleneimine, the present invention uses the graphene oxide-polyethyleneimine to impregnate-extrude-pull melamine foam to obtain the graphene oxide-polyethyleneimine-coated melamine foam.

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

[0048] In the present invention, after the immersion, every 16 cm 2 Preferably, 20 to 24 mL of liquid is absorbed on the melamine foam.

[0049] In the present invention, the pulling preferably further includes heat treatment, and the heat treatment is used to improve the stability of the hydrophilic mass transfer bottom layer.

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

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

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

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

[0054] In the present 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 the present invention, the thickness of the vertical portion of the hydrophilic mass transfer bottom layer is preferably 1 cm.

[0056] In the present invention, the floating structure is preferably hydrophobic foam, and the hydrophobic foam is preferably polystyrene foam. The present invention has no special limitation on the specific size parameters of the floating structure, and parameters well known to those skilled in the art can be used.

[0057] The present invention also provides a method for preparing the photothermal evaporation body 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 bottom layer to form the hydrophobic light-absorbing layer, which is then combined with the floating structure to obtain the photothermal evaporator.

[0059] The present invention has no particular limitation on the specific method of deposition and combination, and methods familiar to those skilled in the art may be used.

[0060] The present invention also provides the use 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 salt water treatment.

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

[0062] In the present 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 the present invention, the salt water treatment is preferably carried out under light, and the intensity of the light is preferably 0.5 to 1.5 kW·m -2 , specifically 0.5, 1 or 1.5 kW·m -2 .

[0064] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0066] Comparative Example 1

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

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

[0069] 2) Covalent cross-linking of alkaline graphene oxide and polyethyleneimine: alkaline graphene oxide and polyethyleneimine are mixed for covalent cross-linking 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 3 hours.

[0070] 3) Immersion-extrusion-pulling: The melamine foam (purchased from Shanghai Beiyou Building Materials Co., Ltd.) was fully immersed in the graphene oxide / polyethyleneimine solution. After immersion, every 16 cm 2 Melamine foam absorbs 24mL of liquid.

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

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

[0073] The simulated brine (salinity 15 wt%) was treated with photothermal evaporation at a light intensity of 1 kW·m -2 Evaporation rate test was carried out under the following conditions: Figure 2 1 is the evaporation rate curve of the brine treated by the photothermal evaporator of comparative example 1, and Table 1 is the data of the change of photothermal pure water production over time.

[0074] Table 1 Comparative Example 1 Photothermal Pure Water Production Data over Time

[0075] Time (h) <![CDATA[Water production rate (kg·m -2 ·h -1 ) <!-- 4 -->]]> 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 were the same as those in Comparative Example 1, as a hydrophilic mass transfer bottom layer;

[0078] A T-shaped photothermal evaporator was prepared: a hydrophilic mass transfer bottom layer (1 cm thick) had a vertical portion and two branches, and the angles between the two branches of the hydrophilic mass transfer bottom layer and the horizontal plane were both set to 0°. A hydrophobic light-absorbing layer PDMS (0.01 cm thick) was deposited on the inner surfaces of the two branches of the hydrophilic mass transfer bottom layer, and then combined with polystyrene foam to obtain a photothermal evaporator.

[0079] The prepared photothermal evaporator was used to treat simulated brine (salinity of 15 wt%) under a light intensity of 1 kW·m -2 Evaporation rate test was carried out under the following conditions: Figure 3 1 is the evaporation rate curve of the salt water treated by the photothermal evaporator in Example 1, and Table 2 is the data of the change of photothermal pure water production over time.

[0080] Table 2 Data of changes in pure water produced by photothermal energy over time in Example 1

[0081] Time (h) <![CDATA[Water production rate (kg·m -2 ·h -1 )]]> 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] The same as Example 1, the only difference is that a Y-shaped photothermal evaporator is prepared: the angle between the two branches of the hydrophilic mass transfer bottom layer and the horizontal plane is 30°.

[0084] The prepared photothermal evaporator was used to treat simulated brine (salinity of 15 wt%) under a light intensity of 1 kW·m -2 Evaporation rate test was carried out under the following conditions: Figure 4 is the evaporation rate curve of the salt water treated by the photothermal evaporator in Example 2, and Table 3 is the data of the change of photothermal pure water production over time.

[0085] Table 3 Data of changes in pure water produced by photothermal energy over time in Example 2

[0086] Time (h) <![CDATA[Water production rate (kg·m -2 ·h -1 )]]> 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] The same as Example 1, the only difference is that a Y-shaped photothermal evaporator is prepared: the angle between the two branches of the hydrophilic mass transfer bottom layer and the horizontal plane is 45°.

[0089] The prepared photothermal evaporator was used to treat simulated brine (salinity of 15 wt%) under a light intensity of 1 kW·m -2 Evaporation rate test was carried out under the following conditions: Figure 5 Table 4 is the evaporation rate curve of the salt water treated by the photothermal evaporator in Example 3, and Table 5 is the data of the change of photothermal pure water production over time.

[0090] Table 4 Data of changes in pure water produced by photothermal energy over time in Example 3

[0091] Time (h) <![CDATA[Water production rate (kg·m -2 ·h -1 )]]> 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] The same as Example 1, the only difference is that a Y-shaped photothermal evaporator is prepared: the angles between the two branches of the hydrophilic mass transfer bottom layer and the horizontal plane are both 60°.

[0094] The prepared photothermal evaporator was used to treat simulated brine (salinity of 15 wt%) under a light intensity of 1 kW·m -2 Evaporation rate test was carried out under the following conditions: Figure 6 Table 5 is the evaporation rate curve of the salt water treated by the photothermal evaporator in Example 4, and Table 6 is the data of the photothermal pure water production changing with time.

[0095] Table 5 Data of changes in pure water produced by photothermal energy over time in Example 4

[0096] Time (h) <![CDATA[Water production rate (kg·m -2 ·h -1 )]]> 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 to 6 As shown in Tables 1 to 5, the central water supply method (Examples 1 to 4) can increase the stability of the material; as the inclination angle increases, the evaporation rate of the material gradually increases and can be maintained at 1.5 kg·m -2 ·h -1 , effectively reducing the damage of salt pollution to material properties and ensuring the efficient and stable treatment performance of the photothermal evaporator for highly concentrated brine.

[0098] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A photothermal evaporation body, characterized in that: include: A hydrophilic mass transfer bottom layer, the hydrophilic mass transfer bottom layer comprising a vertical portion and two branches arranged at the top of the vertical portion, the hydrophilic mass transfer bottom layer passing through the floating structure; A hydrophobic light-absorbing layer is arranged on the upper surfaces of the two branches.

2. The photothermal evaporation body according to claim 1, characterized in that: The two branches have the same included angle with the horizontal plane.

3. The photothermal evaporation body according to claim 2, characterized in that: The angle between the two branches and the horizontal plane is 0-75°.

4. The photothermal evaporation body according to claim 1, characterized in that: The material of the hydrophilic mass transfer bottom layer is melamine foam coated with graphene oxide-polyethyleneimine.

5. The photothermal evaporation body according to claim 1, characterized in that: The material of the hydrophobic light-absorbing layer is polydimethylsiloxane.

6. The photothermal evaporation body according to claim 1, characterized in that: The thickness of the two branches of the hydrophilic mass transfer bottom layer is the same, and the thickness ratio of the two branches to the hydrophobic light absorption layer is 1:0.01-1.

7. The photothermal evaporation body according to claim 1, characterized in that: The floating structure is a hydrophobic foam.

8. The method for preparing a photothermal evaporated product according to any one of claims 1 to 7, characterized in that: The following steps are involved: The hydrophobic light-absorbing layer is deposited on the surface of the hydrophilic mass transfer bottom layer to form the hydrophobic light-absorbing layer, which is then combined with the floating structure to obtain the photothermal evaporator.

9. Use of the photothermal evaporation product according to any one of claims 1 to 7 or the photothermal evaporation product prepared by the preparation method according to claim 8 in salt water treatment.

10. The use according to claim 9, characterized in that: During the salt water treatment, the salt concentration in the salt water to be treated is 0-15wt% and is not zero.

Images