A dihedral interface optical distillation device and its preparation method and application

Abstract

The present invention discloses a dihedral interfacial light distillation device and its preparation method and application. The device includes a carbon black modified PVDF composite membrane as an interfacial light-heat conversion component, a water supply component is provided below the carbon black modified PVDF composite membrane, and a support component is provided below the water supply component. The preparation method is as follows: a carbon black dispersion is sprayed on the hydrophilic side surface of the PVDF composite film to obtain a carbon black modified PVDF composite membrane, a water supply component is placed below the carbon black modified PVDF composite membrane, and a support component is placed below the water supply component. The present invention uses a carbon black modified PVDF composite membrane with unilateral hydrophobicity as an interfacial light-heat conversion component, which has a hydrophobic / hydrophilic two-sided anisotropic interface. Salt cannot reach the evaporation surface of the material, can effectively prevent salt deposition, and can achieve complete brine separation. The present invention has excellent interfacial light distillation performance and salt resistance, and can adapt to the stable treatment of high-salt wastewater.

Description

Technical Field

[0001] The present invention relates to an interface light distillation device, a preparation method and application thereof, and in particular to a dihedral interface light distillation device, a preparation method and application thereof. Background Art

[0002] High-salinity wastewater refers to wastewater with a total dissolved matter (TDS) of 3.5% or more. Its composition is complex and often contains a large amount of Na + Mg 2+ , Ca 2+ 、SO4 2- 、Cl - Ionic and organic pollutants are generally characterized by high salinity, high color, and high toxicity. High-salinity wastewater contains a large amount of organic matter and salts, and direct discharge will seriously damage the ecological environment.

[0003] Currently, treatment technologies used for desalination of saline wastewater can be categorized as thermal evaporation, membrane separation, and natural evaporation. Thermal evaporation, which achieves desalination by heating wastewater and evaporating it, is widely used, mature, and offers stable treatment results and high water recovery rates. However, thermal evaporation technology is limited by factors such as high energy consumption, equipment scaling, and high maintenance costs. Membrane separation utilizes the selective permeability of membranes to achieve desalination, with nanofiltration (NF) and reverse osmosis (RO) being common. Membrane separation operates at room temperature and offers advantages such as a small footprint, ease of maintenance, and simplicity of operation. However, the raw water entering the membrane treatment process requires rigorous pretreatment to meet standards for turbidity, hardness, temperature, and pH; otherwise, membrane fouling and other issues may occur. Natural evaporation, generally referring to evaporation pond technology, is a saline wastewater treatment method that relies solely on natural energy. It utilizes solar energy to evaporate wastewater, with the remaining salt discharged as sludge. It offers advantages such as simple operation and maintenance, good resistance to shock loads, low disposal costs, and a long service life. However, the evaporation pond method is greatly affected by natural conditions, has a low evaporation rate, is difficult to recycle water resources, and has obvious defects.

[0004] The water purification device based on interfacial light distillation technology effectively reduces energy dissipation and achieves a huge improvement in the light-to-steam conversion efficiency. Summary of the Invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a dihedral interfacial light distillation device with excellent interfacial light distillation performance and salt resistance;

[0006] The second object of the present invention is to provide a method for preparing the above-mentioned dihedral interface optical distillation device;

[0007] The third object of the present invention is to provide an application of the above-mentioned dihedral interface light distillation device.

[0008] Technical solution: The dihedral interface light distillation device described in the present invention includes a carbon black modified PVDF composite membrane as an interface light-to-heat conversion component, a water supply component is provided below the carbon black modified PVDF composite membrane, and a support component is provided below the water supply component.

[0009] Wherein, the water supply component is a melamine sponge; the supporting component is a polystyrene foam insulation layer; the water supply component is provided with a downward protruding portion, and the supporting component is provided with a recessed portion matching the protruding portion.

[0010] The method for preparing the dihedral interface optical distillation device comprises the following steps:

[0011] (A) dispersing carbon black powder in a solvent to obtain a carbon black dispersion;

[0012] (B) spraying a carbon black dispersion onto the hydrophilic side surface of the PVDF composite film to obtain a carbon black-modified PVDF composite film;

[0013] (C) A water supply component is placed below the carbon black-modified PVDF composite membrane, and a supporting component is placed below the water supply component to obtain the product.

[0014] Wherein, in step (A), the solvent is ethanol or a mixture of water and ethanol; and the concentration of the carbon black dispersion is 0.1 to 2 mg / ml.

[0015] The specific method of step (B) is as follows: fix the PVDF composite film with the hydrophilic side of the non-woven fabric layer facing upward, and use a pneumatic spray gun to evenly spray the carbon black dispersion onto the film in multiple times, controlling the spraying amount to 0.15-0.85 g / m 2 , obtaining a carbon black modified PVDF composite membrane; cutting the obtained carbon black modified PVDF composite membrane into circles with a diameter of 10-100 mm.

[0016] In step (C), the water supply component is a melamine sponge, and the support component is a polystyrene foam. Specifically, the polystyrene foam is cut to the same size as the carbon black-modified PVDF film, with a square hole cut into the center, the hole accounting for approximately 10% of the total area. The melamine sponge is cut to the same size as the carbon black-modified PVDF film, with a thickness of 2-5 mm. A square protrusion is reserved in the center of the polystyrene foam and inserted into the reserved hole in the polystyrene foam. The melamine sponge is preferably moistened with the raw water to be treated, and the melamine sponge and the carbon black-modified PVDF composite film are applied to each other.

[0017] The application of the above-mentioned dihedral interface optical distillation device in the near-zero discharge of high-salinity wastewater.

[0018] Beneficial effects: Compared with the prior art, the present invention has achieved the following significant effects: (1) The PVDF composite membrane with unilateral hydrophobicity is modified with carbon black as an interface light-heat conversion component, which has a hydrophobic / hydrophilic two-sided anisotropic interface. Salt cannot reach the evaporation surface of the material, which can effectively prevent the phenomenon of salt deposition and achieve complete brine separation. Therefore, the device of the present invention has excellent interface light distillation performance and salt resistance, and can adapt to the stable treatment of high-salt wastewater; (2) The hydrophilic melamine sponge is used as the water supply component and the polystyrene foam insulation layer is used as the supporting component. Through the material and structure The rational design of the structure makes the device not only have high salt removal efficiency and good water quality, but also low cost, small size, low energy consumption and simple maintenance; (3) The photothermal conversion material absorbs solar energy and heats up rapidly, transferring heat to the water at the interface, forming a local high-temperature area and increasing the evaporation rate of water; (4) The interfacial light distillation device limits the solar energy and thermal energy conversion, water heating and water phase change process to a part of the gas-liquid interface, effectively reducing energy dissipation and improving the light energy-steam conversion efficiency; (5) It has broad application prospects in the field of near-zero discharge of high-salinity wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the device of the present invention;

[0020] Figure 2 a is a macroscopic image of the carbon black modified PVDF film of Example 1, b and c are SEM images of the surface of the carbon black modified PVDF film of Example 1, d is an SEM image of the melamine sponge of Example 1, e and f are the contact angles of the hydrophobic and hydrophilic surfaces of the carbon black modified PVDF membrane of Example 1, respectively;

[0021] Figure 3 This is a diagram showing the surface morphology changes and raw water changes of the device in Example 1 during the 8-hour evaporation process;

[0022] Figure 4 This is a graph showing the conductivity changes of raw water and collected water after the device of Example 1 has been running continuously for 8 hours. DETAILED DESCRIPTION

[0023] The present invention will be described in further detail below with reference to the accompanying drawings.

[0024] Example 1

[0025] (1) Dissolve 25 mg of CB powder in 245 ml of water, add 5 ml of ethanol to enhance the solubility of CB, mix well, and ultrasonicate for 3 min to obtain a well-dispersed CB dispersion with a concentration of 0.1 mg / mL.

[0026] (2) Fix the ordinary PVDF composite film on the laboratory table with the hydrophilic side of the non-woven fabric layer facing up. Use a pneumatic spray gun to evenly spray the carbon black dispersion onto the film in multiple times, controlling the spraying amount to 0.15g / m 2 The sprayed film was naturally dried to obtain a carbon black modified PVDF composite membrane.

[0027] (3) Cut the carbon black modified PVDF composite film obtained in (2) into a circle with a diameter of 10 mm. Cut the polystyrene foam to the same size as the PVDF film and cut a square hole in the middle. The area of ​​the hole accounts for about 10% of the total area. Cut the melamine sponge to the same size as the film and control the thickness to 2 mm. Reserve a square raised interface in the center of the foam and insert it into the reserved hole in the polystyrene foam. Wet the melamine sponge with the raw water to be treated. Apply the dihedral film to the hydrophilic melamine sponge and polystyrene insulation foam to form an interfacial light distillation device.

[0028] Figure 1 This is a design diagram of a salt water separation experimental device, which includes a carbon black modified PVDF composite membrane 1, a water supply component 2, a support component (not shown), a culture dish 3, and wastewater 4. Figure 1 A petri dish is used to simulate a shallow pool. Because the water layer is very shallow, no foam is needed for support and the heat dissipation effect is small. The polystyrene insulation foam is removed, and the performance is close to that of the original device, which can better reflect its brine separation effect.

[0029] A light distillation experiment was conducted on the device to test its water evaporation performance. The results are as follows:

[0030] The evaporation rate of the device reached 1.22 kg / m3 within 8 hours by using saturated sodium chloride solution to simulate high-salt wastewater. 2 / h, and the photothermal conversion efficiency is 81.69%.

[0031] Depend on Figure 2 From a in the figure, we can see that the PVDF film after spraying carbon black has good light absorption in the visible light region; Figure 2 From b and c in the figure, we can see that the PVDF film is assembled from fibers; Figure 2 From the d in the figure, we can see that melamine foam has a porous network structure. Figure 2 As can be seen from Figures e and f, the upper and lower sides of PVDF exhibit different hydrophilic and hydrophobic properties.

[0032] Depend on Figure 3 It can be seen that when this experimental device was used for continuous treatment of high-salt wastewater for 8 hours, no salt was precipitated on the surface of the absorber, which confirmed the stability of the device.

[0033] Depend on Figure 4 It can be seen that the conductivity of the water obtained after treatment with wastewater and high-concentration salt water by this device is greatly reduced, proving that it can be used for clean water production.

[0034] Example 2

[0035] (1) Dissolve 25 mg of CB powder in 20 ml of water, add 5 ml of ethanol and water mixture to enhance the solubility of CB, mix well and ultrasonicate for 15 min to obtain a well-dispersed CB dispersion with a concentration of 1 mg / mL.

[0036] (2) Fix the ordinary PVDF composite film on the laboratory table with the hydrophilic side of the non-woven fabric layer facing up. Use a pneumatic spray gun to evenly spray the carbon black dispersion onto the film in multiple times, controlling the spraying amount to 0.50g / m 2 The sprayed film was naturally dried to obtain a carbon black modified PVDF composite membrane.

[0037] (3) Cut the carbon black modified PVDF composite film obtained in (2) into a circle with a diameter of 40 mm. Cut the polystyrene foam to the same size as the PVDF film and cut a square hole in the middle. The area of ​​the hole accounts for about 10% of the total area. Cut the melamine sponge into the same size as the film and control the thickness to 3 mm. Reserve a square raised interface in the center of the foam and insert it into the reserved hole in the polystyrene foam. Wet the melamine sponge with the raw water to be treated. Apply the dihedral film to the hydrophilic melamine sponge and polystyrene insulation foam to form an interfacial light distillation device.

[0038] A light distillation experiment was conducted on the device to test its water evaporation performance. The results are as follows:

[0039] The evaporation rate of the device reached 1.24 kg / m3 within 8 hours by using saturated sodium chloride solution to simulate high-salt wastewater. 2 / h, and the photothermal conversion efficiency is 83.14%.

[0040] Example 3

[0041] (1) Dissolve 25 mg of CB powder in 7.5 ml of water, add 5 ml of ethanol and water mixture to enhance the solubility of CB, mix well and ultrasonicate for 30 min to obtain a well-dispersed CB dispersion with a concentration of 2 mg / mL.

[0042] (2) Fix the ordinary PVDF composite film on the laboratory table with the hydrophilic side of the non-woven fabric layer facing up. Use a pneumatic spray gun to evenly spray the carbon black dispersion onto the film in multiple times, controlling the spraying amount to 0.85g / m 2 The sprayed film was naturally dried to obtain a carbon black modified PVDF composite membrane.

[0043] (3) Cut the carbon black modified PVDF composite film obtained in (2) into a circle with a diameter of 100 mm. Cut the polystyrene foam to the same size as the PVDF film and cut a square hole in the middle, with the area of ​​the hole accounting for approximately 10% of the total area. Cut the melamine sponge into the same size as the film and control the thickness to 5 mm. Reserve a square raised interface in the center of the foam and insert it into the reserved hole in the polystyrene foam. Moisten the melamine sponge with the raw water to be treated, and apply the dihedral film to the hydrophilic melamine sponge and polystyrene insulation foam to form an interfacial light distillation device.

[0044] A light distillation experiment was conducted on the device to test its water evaporation performance. The results are as follows:

[0045] The evaporation rate of the device reached 1.27 kg / m3 within 8 hours by using saturated sodium chloride solution to simulate high-salt wastewater. 2 / h, and the photothermal conversion efficiency is 85.73%.

[0046] Example 4

[0047] (1) Dissolve 25 mg of CB powder in 45 ml of water, add 5 ml of ethanol to enhance the solubility of CB, mix well, and then ultrasonicate for 15 min to obtain a well-dispersed CB dispersion with a concentration of 0.5 mg / mL.

[0048] (2) Fix the ordinary PVDF composite film on the laboratory table with the hydrophilic side of the non-woven fabric layer facing up. Use a pneumatic spray gun to evenly spray the carbon black dispersion onto the film in multiple times, controlling the spraying amount to 0.45g / m 2 The sprayed film was naturally dried to obtain a carbon black modified PVDF composite membrane.

[0049] (3) Cut the carbon black modified PVDF composite film obtained in (2) into a circle with a diameter of 30 mm. Cut the polystyrene foam to the same size as the PVDF film and cut a square hole in the middle. The area of ​​the hole accounts for about 10% of the total area. Cut the melamine sponge to the same size as the film and control the thickness to 3 mm. Reserve a square raised interface in the center of the foam and insert it into the reserved hole in the polystyrene foam. Wet the melamine sponge with the raw water to be treated. Apply the dihedral film to the hydrophilic melamine sponge and polystyrene insulation foam to form an interfacial light distillation device.

[0050] Configure simulated high-salinity wastewater, where Na + Content 35000mg / L, Ca 2+ Content 850mg / L, Cl - Content 25650mg / L, SO4 2- The content is 40100mg / L, COD content is 2000mg / L, TDS content is 101650mg / L. The organic waste material is simulated with methyl orange.

[0051] A light distillation experiment was conducted on the device to test its water evaporation performance. The results are as follows:

[0052] The prepared simulated high-salt wastewater was used as raw water to test Example 4. Within 8 hours, the evaporation rate of the device was 1.08 kg / m 2 / h, and the photothermal conversion efficiency is 71.28%.

[0053] Example 5

[0054] (1) Dissolve 25 mg of CB powder in 20 ml of water, add 5 ml of ethanol and water mixture to enhance the solubility of CB, mix well and ultrasonicate for 20 min to obtain a well-dispersed CB dispersion with a concentration of 1 mg / mL.

[0055] (2) Fix the ordinary PVDF composite film on the experimental table with the hydrophilic side of the non-woven fabric layer facing up. Use a pneumatic spray gun to evenly spray the carbon black dispersion onto the film in multiple times, controlling the spraying amount to 0.5g / m 2 The sprayed film was naturally dried to obtain a carbon black modified PVDF composite membrane.

[0056] (3) Cut the carbon black modified PVDF composite film obtained in (2) into a circle with a diameter of 70 mm. Cut the polystyrene foam to the same size as the PVDF film and cut a square hole in the middle. The area of ​​the hole accounts for about 10% of the total area. Cut the melamine sponge to the same size as the film and control the thickness to 4 mm. Reserve a square raised interface in the center of the foam and insert it into the reserved hole in the polystyrene foam. Wet the melamine sponge with the raw water to be treated. Apply the dihedral film to the hydrophilic melamine sponge and polystyrene insulation foam to form an interfacial light distillation device.

[0057] A light distillation experiment was conducted on the device to test its water evaporation performance. The results are as follows:

[0058] The prepared simulated high-salt wastewater was used as raw water to test Example 5. Within 8 hours, the evaporation rate of the device was 1.09 kg / m 2 / h, and the photothermal conversion efficiency is 72.31%.

[0059] Example 6

[0060] (1) Dissolve 25 mg of CB powder in 7.5 ml of water, add 5 ml of ethanol and water mixture to enhance the solubility of CB, mix well and ultrasonicate for 30 min to obtain a well-dispersed CB dispersion with a concentration of 2 mg / mL.

[0061] (2) Fix the ordinary PVDF composite film on the laboratory table with the hydrophilic side of the non-woven fabric layer facing up. Use a pneumatic spray gun to evenly spray the carbon black dispersion onto the film in multiple times, controlling the spraying amount to 0.85g / m 2 The sprayed film was naturally dried to obtain a carbon black modified PVDF composite membrane.

[0062] (3) Cut the carbon black modified PVDF composite film obtained in (2) into a circle with a diameter of 100 mm. Cut the polystyrene foam to the same size as the PVDF film and cut a square hole in the middle, with the area of ​​the hole accounting for approximately 10% of the total area. Cut the melamine sponge into the same size as the film and control the thickness to 5 mm. Reserve a square raised interface in the center of the foam and insert it into the reserved hole in the polystyrene foam. Moisten the melamine sponge with the raw water to be treated, and apply the dihedral film to the hydrophilic melamine sponge and polystyrene insulation foam to form an interfacial light distillation device.

[0063] A light distillation experiment was conducted on the device to test its water evaporation performance. The results are as follows:

[0064] The prepared simulated high-salt wastewater was used as raw water to test Example 6. Within 8 hours, the evaporation rate of the device was 1.12 kg / m 2 / h, and the photothermal conversion efficiency is 74.55%.

Claims

1. A dihedral interface optical distillation device for near-zero discharge of high-salinity wastewater, characterized in that: The dihedral interface light distillation device comprises a carbon black modified PVDF composite membrane (1) as an interface light-heat conversion component, wherein the carbon black modified PVDF composite membrane (1) is obtained by spraying a carbon black dispersion onto the hydrophilic side surface of the PVDF composite membrane with a non-woven fabric fiber layer attached; the hydrophilic side of the PVDF composite membrane with a non-woven fabric fiber layer is upward, and the PVDF film in the PVDF composite membrane is assembled from fibers; the upper side and the lower side of the carbon black modified PVDF composite membrane (1) exhibit different hydrophilic and hydrophobic properties, the contact angle of the hydrophobic surface on the lower side is 123.5°, and the contact angle of the hydrophilic surface on the upper side is 36.8°; a water supply component (2) is provided below the carbon black modified PVDF composite membrane (1), and a support component is provided below the water supply component (2); The method for preparing the dihedral interface optical distillation device comprises the following steps: (A) dispersing carbon black powder in a solvent to obtain a carbon black dispersion; (B) spraying a carbon black dispersion onto the hydrophilic side surface of the PVDF composite membrane with the non-woven fabric layer to obtain a carbon black modified PVDF composite membrane (1); (C) placing a water supply component (2) below the carbon black modified PVDF composite membrane (1), and placing a supporting component below the water supply component (2), to obtain; The water supply component (2) is a melamine sponge, and the supporting component is a polystyrene foam insulation layer; A square hole is cut in the middle of the polystyrene foam insulation layer, and the melamine sponge is cut into a size equal to that of the carbon black modified PVDF composite film (1). A square raised interface is reserved in the center of the melamine sponge and inserted into the reserved hole of the polystyrene foam insulation layer.

2. The dihedral interface optical distillation device for near-zero discharge of high-salinity wastewater according to claim 1, characterized in that: The water supply component (2) is provided with a downwardly extending portion, and the supporting component is provided with a recessed portion matching the extending portion.

3. A method for preparing a dihedral interface optical distillation device for near-zero discharge of high-salinity wastewater according to claim 1, characterized in that: The following steps are involved: (A) dispersing carbon black powder in a solvent to obtain a carbon black dispersion; (B) spraying a carbon black dispersion onto the hydrophilic side surface of the PVDF composite membrane with the non-woven fabric layer to obtain a carbon black modified PVDF composite membrane (1); (C) placing a water supply component (2) below the carbon black modified PVDF composite membrane (1), and placing a supporting component below the water supply component (2), to obtain; The water supply component (2) is a melamine sponge, and the supporting component is a polystyrene foam insulation layer; A square hole is cut in the middle of the polystyrene foam insulation layer, and the melamine sponge is cut into a size equal to that of the carbon black modified PVDF composite film (1). A square raised interface is reserved in the center of the melamine sponge and inserted into the reserved hole of the polystyrene foam insulation layer.

4. The method for preparing a dihedral interface optical distillation device for near-zero discharge of high-salinity wastewater according to claim 3, characterized in that: In step (A), the concentration of the carbon black dispersion is 0.1-2 mg / ml.

5. The method for preparing a dihedral interface optical distillation device for near-zero discharge of high-salinity wastewater according to claim 3, characterized in that: In step (C), the thickness of the melamine sponge is 2-5 mm.

6. The method for preparing a dihedral interface optical distillation device for near-zero discharge of high-salinity wastewater according to claim 3, characterized in that: In step (B), the spraying amount is controlled to be 0.15-0.85 g / m 2 .

7. The method for preparing a dihedral interface optical distillation device for near-zero discharge of high-salinity wastewater according to claim 3, characterized in that: In step (C), the melamine sponge is moistened with the raw water to be treated, so that the melamine sponge and the carbon black modified PVDF composite membrane (1) are attached to each other.

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