An oil-water separation device based on spontaneous electricity control of electrically heated switchable wettability surface and a separation method thereof

Abstract

The application discloses a kind of high-efficiency oil-water separation devices and separation methods of electric heating switching wettable surface based on spontaneous power control, and the device includes oil-water separator, and oil-water separator from top to bottom includes the multiphase oil-water cavity, separation interlayer, power generation interlayer and single-phase liquid cavity arranged in sequence, separation interlayer inside contains patterned superamphiphobicity / thermal response superwetting droplet separation film, it is with porous metal net as base, and the patterned surface coating of base is composed of thermal response superwetting separation film material and superamphiphobic material, changes the temperature of its surface under the energized state of porous metal net base, can realize the wettability of the surface of separation film material to oil and water changes, to realize the selective separation of oil-water mixture;Power generation interlayer inside contains droplet power generation unit.The device of the application realizes intelligent accurate control and the oil-water separation process of no power consumption by the linkage combination of droplet power generation and electric heating response superwetting oil-water separation film.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil-water separation, and particularly relates to an oil-water separation device based on electric heating switching wettability surface controlled by self-generation and a separation method thereof. BACKGROUND

[0002] With the rapid development of global oil transportation, the frequency of oil leakage in the petrochemical industry is increasing. Water pollution and ecological disaster caused by oil leakage have become a major problem in environmental protection. In addition, a large amount of waste oil-water mixture will be produced in the process of daily production and life, such as chemical water / oil pollutant discharge, kitchen oil pollutant discharge, etc. If the oil-containing wastewater is not effectively treated, it will cause great harm to biology and environment. At present, the oil-water separation methods mainly include biomass agent, adsorption material, filtration, centrifugation and other methods, but the above methods need frequent equipment maintenance and replacement of parts, and at the same time, large devices containing motors such as water pumps are needed to provide power for the overall system, which makes it face the bottleneck problems of large energy consumption, complex operation and low efficiency when treating oil-water pollutants.

[0003] The membrane separation method using super-wetting material has the characteristics of low energy consumption, high efficiency and simple system. It mainly uses the principle of large surface tension difference between oil and water and different affinity of super-wetting material surface to oil and water, so that it can selectively absorb one phase of oil or water and intercept the other phase. At present, the traditional membrane separation device can be divided into single-wetting membrane separation device and double-wetting membrane separation device according to the wettability of the separation membrane. The separation membrane in the single-wetting membrane separation device only has one kind of wettability, so it can only separate one phase of the oil-water mixture, while the other phase will remain on the surface of the separation membrane, which will prevent the continuous separation of the oil-water mixture and greatly reduce the separation efficiency. The conventional double-wetting membrane separation device is composed of two kinds of separation membranes with opposite wettability. The two kinds of separation membranes can separate oil phase or water phase respectively, and continuous oil-water separation is carried out to improve the separation efficiency. However, due to the existence of two kinds of separation membranes with opposite wettability, the preparation difficulty and manufacturing process of the separation membrane are greatly increased. In addition, the traditional membrane separation device controls the start and stop of the oil-water separation process through an electric valve, which needs to provide a complex external power supply device, so as to increase the external power consumption of the overall device.

[0004] The application provides an intelligent change type double-wetting membrane separation device based on spontaneous electricity generation control of an electrothermal response super-wetting material surface. The device comprises an electrothermal response super-wetting oil-water separation surface and a liquid drop power generation surface. First, the device can control the reversible conversion of the wetting property of the separation membrane surface between air super-hydrophilic and water super-oleophobicity under water and air super-hydrophobic and water super-oleophilic under water at different temperatures, so that the separation of one phase of the mixture is completed in the separation process; then, the separation of the other phase is continued by changing the wetting property of the separation membrane by electrothermal response. The continuity of the separation process and the start and stop of the separation process are realized by changing the wetting property of the separation membrane. On the other hand, the liquid drop power generation surface can realize the collection and reuse of potential energy in the separation of water drops, and provide the required electric energy for the change of the wetting property of the separation membrane, so that the whole device realizes free energy supply without external power consumption. The application makes up for the shortcomings of the single-wetting membrane separation device, such as the inability to continuously separate, and the conventional double-wetting membrane separation device, such as the high technical requirements and complex manufacturing process of the separation membrane. The simple power generation end of the device avoids the problems of complex energy supply end device and energy supply difficulty.

[0005] In summary, the device provides an electrothermal response control method for oil-water separation with adjustable wetting property, which makes the control process of oil-water separation more active, accurate and intelligent. At the same time, the self-power generation device realizes self-sufficient energy supply. Therefore, the device realizes intelligent and accurate control and power-free oil-water separation process by combining liquid drop power generation with electrothermal response super-wetting oil-water separation membrane. SUMMARY

[0006] In view of the above technical problems existing in the prior art, the purpose of the application is to provide an oil-water separation device with electrothermal switchable wetting surface based on self-power generation control and a separation method thereof. The application uses the difference in surface tension of oil and water to realize oil-water separation through an electrothermal response super-wetting oil-water separation membrane (i.e. patterned super-amphiphobic / thermal response super-wetting drop separation membrane). At the same time, by using the principle of contact electrification and electrostatic induction, a liquid drop power generation unit based on interface effect and switching effect is established to provide the required electric energy for the separation membrane surface, realize the change of wetting property, and realize the collection and reuse of energy in the separation of water drops. The application has low energy consumption, small occupied area and low cost, and is particularly suitable for low-energy oil-water separation of oil spill, chemical wastewater, and intelligent controllable oil-water separation in areas where electric energy cannot be supplied in time, such as offshore areas.

[0007] The technical scheme adopted by the application is as follows:

[0008] An oil-water separation device based on self-power generation control of electrothermal switching wettability surface, comprising a communication valve, a residue filter and an oil-water separator connected by pipelines in sequence, wherein the oil-water separator comprises a multiphase oil-water cavity, a separation interlayer, a power generation interlayer and a single-phase liquid cavity arranged in sequence from top to bottom, the top of the multiphase oil-water cavity is provided with an exhaust valve and a pressure gauge, and the bottom of the single-phase liquid cavity is provided with a liquid outlet and a liquid outlet valve.

[0009] The separation interlayer comprises a patterned superamphiphobic / thermo-responsive superwetting droplet separation film, which is based on a porous metal mesh, the patterned surface coating of the substrate is composed of a thermo-responsive superwetting separation film material and a superamphiphobic material, and the surface of the separation film material changes in wettability to oil and water under the condition of power supply to the porous metal mesh substrate, so as to realize selective separation of oil-water mixture.

[0010] The outer side of the separation interlayer is provided with a power switch, and the outer side wall of the power generation interlayer is provided with a power supply, the power generation interlayer comprises a droplet power generation unit, the droplet power generation unit is connected with the power supply through wires, the water droplets separated by the separation interlayer impact the surface of the droplet power generation unit to generate electric charge, realizing the conversion of gravitational potential energy and electric energy of the droplets, and the converted electric energy can be stored to the power supply, the power supply is connected with the porous metal mesh substrate of the patterned superamphiphobic / thermo-responsive superwetting droplet separation film through wires and a power switch, and can supply power to the porous metal mesh substrate, so as to realize the efficient oil-water separation process of the electrothermal switching wettability surface based on self-power generation control. Figure 2 The droplet power generation unit and the porous metal mesh substrate of the patterned superamphiphobic / thermo-responsive superwetting droplet separation film are connected in parallel through wires and a power supply.

[0011] Further, a plurality of circular coating of thermo-responsive superwetting separation film materials are arranged on the surface of the substrate, the coating thickness of the thermo-responsive superwetting separation film material is 100-150 mu m, and the rest of the surface is superamphiphobic material; the thermo-responsive superwetting separation film material is a temperature-sensitive material, which can stably and reversibly change between air superhydrophilic-underwater superoleophobic and air superhydrophobic-underwater superoleophilic states under temperature conversion, and the transition temperature is 30-35 DEG C; the superamphiphobic material continuously maintains the superamphiphobic state under the condition of changing temperature.

[0012] Further, the process of preparing the thermo-responsive superwetting separation film material on the surface of the porous metal mesh substrate is as follows:

[0013] 1) Preparation of copolymer poly-block poly: initiator PMMA-Br, red copper powder, N2H4·H2O, Me6TREN and carboxylated carbon nanotubes are added to organic solvent A, after stirring for 2-10 min, N-isopropyl acrylamide NIPAAm is added, and the polymerization reaction is carried out at 40-70℃; after the reaction is completed, the catalyst is removed, and the polymerization product is repeatedly precipitated from anhydrous ether, and dried to obtain the copolymer poly-block poly, which is PMMA-b-NIPAAm block copolymer;

[0014] 2) Preparation of PMMA-b-PNIPAAm fiber membrane by electrospinning method: PMMA-b-NIPAAm block copolymer is dissolved in organic solvent B, after stirring for 10-40 h, the prepared solution is electrospun in a closed chamber; during the electrospinning process, the applied voltage is kept at 10-20 kV, the original spinning fiber is collected with a circular porous metal mesh, and the obtained fiber membrane is dried to remove the residual solvent, i.e. preparation is completed.

[0015] Further, in step 1), the feeding ratio of initiator PMMA-Br, red copper powder, N2H4·H2O, Me6TREN and carboxylated carbon nanotubes is 200-400 mg: 1-2 mg: 1-1.5 μL: 5-10 μL: 10-15 mg, preferably 300 mg: 1.5-1.6 mg: 1.1-1.2 μL: 7-7.5 μL: 10-12 mg.

[0016] Further, in step 1), the organic solvent A is a mixed solvent of DMF / 2-propanol, and the volume ratio of the two is 1~4:1, preferably 2:1; in step 2), the organic solvent B is a mixed solvent of DMF / chloroform, and the volume ratio of the two is 1:1~4, preferably 1:2, and the mass concentration of PMMA-b-NIPAAm in the organic solvent is 20-25%.

[0017] Further, the circular coating arranged on the surface of the porous metal mesh substrate as the thermal responsive super-wetting separation membrane material has a circular diameter of 1-3 mm, and the adjacent interval is 1-2 mm.

[0018] Further, the super-amphiphobic material includes titanium dioxide and fluorine ST-110, and the feeding ratio of the two is 1 g: 0.8~1.2 mL;

[0019] The preparation method of the super-amphiphobic material on the surface of the porous metal mesh substrate is as follows: after the thermal responsive super-wetting separation membrane material is prepared on the surface of the porous metal mesh substrate, fluorine-titanium dioxide suspension solution is sprayed on the basis of the thermal responsive super-wetting separation membrane material by mask method, the mask is circular, the circular diameter is 1-3 mm, and the interval is 1-2 mm, and the specific preparation process is as follows:

[0020] S1: titanium dioxide is added to anhydrous ethanol and ultrasonically dispersed, then fluoride ST-110 is added, stirred uniformly, and reacted at room temperature for 5-7 h to prepare a fluoride-titanium dioxide suspension solution by hydrolysis and condensation of titanium dioxide and ST-110;

[0021] S2: a mask is performed on the thermally responsive super-wetting separation film material on the surface of the porous metal mesh substrate, then the surface of the thermally responsive super-wetting separation film material is sprayed with the fluoride-titanium dioxide suspension solution using a spray pen to prepare a super-amphiphobic coating, the water droplet contact angle of the super-amphiphobic coating in air is 145-155°, and the hysteresis angle is 4-6°, the oil droplet contact angle of the super-amphiphobic coating in air is 145-155°, and the hysteresis angle is 4-6°, and the thickness of the super-amphiphobic coating is 80-150 μm.

[0022] A separation method of an oil-water separation device based on self-power generation control of an electrothermal switching wetting surface, when the separation object is a light oil-water mixture, the separation steps are as follows:

[0023] 1) open the exhaust valve at the top of the multi-phase oil-water chamber;

[0024] 2) open the front end communication valve of the residue filter;

[0025] 3) under the action of gravity, the light oil-water mixture first enters the residue filter to separate the solid impurities contained in the mixture;

[0026] 4) the light oil-water mixture enters the multi-phase oil-water chamber, and after the light oil-water mixture is completely introduced, the front end communication valve of the residue filter is closed;

[0027] 5) the light oil-water mixture contacts the patterned super-amphiphobic / thermally responsive super-wetting droplet separation film in the separation interlayer, the surface of the patterned super-amphiphobic / thermally responsive super-wetting droplet separation film at room temperature is a patterned super-amphiphobic / air super-hydrophilic-underwater super-oleophobic surface, and since the water in the mixture is in the lower layer, it directly penetrates the patterned super-amphiphobic / thermally responsive super-wetting droplet separation film, while the light oil cannot penetrate the patterned super-amphiphobic / thermally responsive super-wetting droplet separation film, thereby realizing separation of the light oil-water mixture;

[0028] 6) the separated water droplets fall onto the liquid droplet power generation unit surface of the power generation interlayer, converting the potential energy of the water droplets into electrical energy to charge the power supply outside the power generation interlayer;

[0029] 7) as the water in the multi-phase oil-water chamber is completely separated, the liquid outlet valve at the bottom of the single-phase liquid chamber is opened to completely discharge the separated water, and then the liquid outlet valve is closed;

[0030] 8) Finally, turn on the power switch outside the separation sandwich, heat the patterned superamphiphobic / thermoresponsive superwetting droplet separation membrane, and make the separation membrane change from the superamphiphobic / air superhydrophilic-underwater superoleophobic patterned surface to the superamphiphobic / air hydrophobic-underwater oleophilic patterned surface, so that the remaining oil phase in the multi-phase oil-water cavity can pass through the separation membrane and enter the single-phase liquid cavity and be discharged.

[0031] A separation method of an oil-water separation device based on self-power control of electrothermal switching wettability surface, when the separation object is heavy oil-water mixture, the separation steps are as follows:

[0032] 1) Turn on the power switch outside the separation sandwich, heat the patterned superamphiphobic / thermoresponsive superwetting droplet separation membrane, and make the separation membrane change from the superamphiphobic / air superhydrophilic-underwater superoleophobic patterned surface to the superamphiphobic / air hydrophobic-underwater oleophilic patterned surface;

[0033] 2) Turn on the exhaust valve at the top of the multi-phase oil-water cavity;

[0034] 3) Turn on the communication valve at the front end of the filter;

[0035] 4) Under the action of gravity, the heavy oil-water mixture first enters the filter to separate the solid impurities contained in the mixture;

[0036] 5) The heavy oil-water mixture enters the multi-phase oil-water cavity, and after the heavy oil-water mixture is completely introduced, the communication valve at the front end of the filter is closed;

[0037] 6) The heavy oil-water mixture contacts the patterned superamphiphobic / thermoresponsive superwetting droplet separation membrane in the separation sandwich, and under the heating condition, the surface of the separation membrane is a superamphiphobic / air hydrophobic-underwater oleophilic patterned surface, so the heavy oil in the mixture directly passes through the separation membrane, while the water cannot pass through the separation membrane, thereby realizing the separation of the heavy oil-water mixture;

[0038] 7) Turn on the liquid outlet valve at the bottom of the single-phase liquid cavity to completely discharge the separated heavy oil, and then close the liquid outlet valve;

[0039] 8) Finally, turn off the power switch outside the separation sandwich, and make the separation membrane change from the superamphiphobic / air hydrophobic-underwater oleophilic patterned surface to the superamphiphobic / air superhydrophilic-underwater superoleophobic patterned surface, so that the remaining water phase in the multi-phase oil-water cavity can pass through the separation membrane and enter the single-phase liquid cavity and be discharged.

[0040] Compared with the prior art, the present application has the following beneficial effects:

[0041] (1) The patterned superamphiphobic / thermoresponsive superwetting droplet separation membrane can realize rapid and efficient separation of oil-water mixture;

[0042] (2) The present application realizes the collection of the potential energy of the separated liquid and self-reuse by using the liquid drop power generation surface;

[0043] (3) The present application realizes the intelligent continuous separation of the oil-water mixture by the single piece of separation membrane through changing the surface wettability by using the heat responsive super-wetting surface, without using multiple pieces of different wettability membranes, thereby reducing the workload and related technical requirements;

[0044] (4) The present application can realize the intelligent continuous separation of light oil-water, heavy oil-water, light oil-water-heavy oil and the like;

[0045] (5) The present application realizes the oil-water separation under ultra-low power consumption by changing the surface wettability through the liquid drop power generation, without external function. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 It is a structural schematic view of an oil-water separation device based on a self-power generation controlled electrothermal switching wettability surface of the present application;

[0047] Figure 2 It is a whole circuit connection relationship schematic view of a patterned super-amphiphilic / heat responsive super-wetting drop-shaped separation membrane (referred to as heat responsive oil-water separation membrane) in a separation interlayer, a liquid drop power generation unit in a power generation interlayer and a power supply of the present application;

[0048] Figure 3 It is a structural schematic view of a power generation interlayer containing a liquid drop power generation unit of the present application;

[0049] Figure 4 It is a vertical section structural schematic view of the structure; Figure 3

[0050] Figure 5 It is a surface structure schematic view of a patterned super-amphiphilic / heat responsive super-wetting drop-shaped separation membrane of the present application. DETAILED DESCRIPTION

[0051] The present application will be further described below in combination with specific embodiments, but the protection scope of the present application is not limited thereto.

[0052] Example: Control Figures 1-5

[0053] An oil-water separation device based on a self-power generation controlled electrothermal switching wettability surface, comprising a communication valve 2, a residue filter 3, a buffer tank and an oil-water separator connected by pipelines in sequence, wherein the oil-water separator comprises a multi-phase oil-water cavity 6, a separation interlayer 8, a power generation interlayer 10 and a single-phase liquid cavity 13 arranged in sequence from top to bottom, the multi-phase oil-water cavity 6 is provided with an exhaust valve 5 and a pressure gauge 4 at the top, and the single-phase liquid cavity 13 is provided with a liquid outlet 11 and a liquid outlet valve 12 at the bottom. ​

[0054] The separation interlayer 8 contains a thermal response type dual-wetting film separation membrane (i.e. a patterned super-amphiphobic / thermal response type super-wetting droplet separation membrane) inside. The porous metal mesh is used as the substrate, and the patterned surface coating of the substrate is composed of thermal response type super-wetting separation membrane material 19 and super-amphiphobic material 20. A plurality of circular coatings are arranged on the surface of the substrate, and the material of the circular coatings is thermal response type super-wetting separation membrane material 19, and the rest of the surface is super-amphiphobic material 20.

[0055] The temperature of the porous metal mesh substrate can be changed when it is powered on, which can change the wettability of the thermal response type super-wetting separation membrane material to oil and water, thereby realizing the selective separation of oil-water mixture. The separation interlayer 8 is provided with a power switch 7 on the outside, and the power supply 9 is provided on the outer side wall of the power generation interlayer 10. The power generation interlayer 10 contains a droplet power generation unit inside, which is connected to the power supply 9 through wires. The water droplets separated by the separation interlayer 8 can generate electric charge by impacting the surface of the droplet power generation unit, realizing the conversion of gravitational potential energy and electric energy of the droplets, and the converted electric energy can be stored in the power supply 9. The power supply 9 is connected to the porous metal mesh substrate of the patterned super-amphiphobic / thermal response type super-wetting droplet separation membrane through wires and a power switch 7, and can supply power to the porous metal mesh substrate to realize the oil-water separation process of the electrically heated switchable wetting surface. Figure 2 The droplet power generation unit and the porous metal mesh substrate of the patterned super-amphiphobic / thermal response type super-wetting droplet separation membrane are connected in parallel through wires and a power supply.

[0056] In the present application, the filter 3 is connected to the liquid inlet pipe 1 through the communication valve 2 at the front end and connected to the liquid inlet of the multi-phase oil-water cavity 6 through the flange at the rear end, which is used to separate the solid impurities in the liquid and prevent the separation device from being blocked. The multi-phase oil-water cavity 6 is provided with an exhaust valve 5 and a pressure gauge 4 at the top, and a left side liquid inlet, which is used to display and maintain the constant pressure inside the device, and maintain the input of oil-water mixture. The oil-water separation interlayer contains an electrically heated switchable wetting patterned surface inside to realize the single-phase selective separation of oil and water. The power generation interlayer can convert the potential energy of the droplets into electric energy for reuse. The single-phase liquid cavity is composed of a main cavity and a liquid outlet 11 and a liquid outlet valve 12 at the bottom, which is mainly used to collect and discharge the separated liquid.

[0057] The application is based on an oil-water separation device of self-generating electrically heated switchable wetting surface, wherein the oil-water separation layer is driven by gravity, the separation membrane of the electrically heated switchable wetting porous metal mesh surface is constructed, the porous metal mesh is communicated with an external power supply and a power switch through wires, the temperature of the porous metal mesh surface is changed in the power-on state, the wetting of the surface to oil and water changes, and thus the selective separation of the oil-water mixture is realized. The power generation sandwich utilizes the contact electrification and electrostatic induction principle to establish a droplet power generation unit based on the interface effect and switching effect, charges are generated by the separated droplets impacting the power generation surface, the conversion of the gravitational potential energy of the droplets and the electric energy is realized, the circuit is connected with an external power supply, and the generated electric energy is introduced into the power storage.

[0058] The filter residue device 3 is composed of a first filter and a second filter made of two metal meshes with different pore sizes, and separates the solid impurities contained in the oil-water mixture to prevent the clogging of the separator body, wherein the metal meshes are 200-800 mesh metal meshes, and the pore size of the first filter is larger than that of the second filter.

[0059] The oil-water separation sandwich contains a patterned superamphiphobic / thermally responsive superwetting droplet separation membrane, internal circuit wires and a power switch inside, the power switch is fixed on the outside of the oil-water separation sandwich by bolts, and is used to turn on the circuit. The upper part of the oil-water separation sandwich is connected with the multiphase oil-water cavity, and the lower part of the oil-water separation sandwich is connected with the top of the power generation sandwich, wherein the connection parts are connected by flanges and are sealed with sealing rings.

[0060] Comparison Figure 5 The surface coating of the thermally responsive dual-wetting separation membrane is composed of a thermally responsive superwetting separation membrane material 19 (coating thickness is 100-150 μm) and a superamphiphobic material 20 (coating thickness is 80-150 μm), the thermally responsive superwetting separation membrane material 19 is a temperature-sensitive material, which can stably and reversibly change the surface between the superhydrophilic-air superoleophobic and superhydrophobic-air superphilic oil two states under temperature conversion, and the transition temperature is 30-35℃; the superamphiphobic material 20 continuously maintains the superamphiphobic state under the condition of changing temperature.

[0061] The patterned superhydrophobic / thermally responsive superwetting droplet separation membrane of this invention uses a metal mesh as a substrate, with a portion of its surface being a thermally responsive superwetting surface. As a temperature-sensitive material, the surface can stably and reversibly transition between two states: air superhydrophilic-underwater superoleophobic and air superhydrophobic-underwater superoleophilic, with a transition temperature of 30-35°C. Simultaneously, the surface, through the conductivity of the metal substrate and carboxylated carbon nanotubes, can convert electrical energy into heat energy for system utilization. The remaining surface portion maintains its superhydrophobic / thermally responsive state under varying temperatures. The patterned superhydrophobic / thermally responsive superwetting droplet separation surface promotes continuous liquid droplet separation, enabling the generation of electricity by a power generation device.

[0062] The thermally responsive superwetting surface of the present invention is prepared by electrospinning of temperature-responsive copolymer poly(methyl methacrylate)-block poly(n-isopropylacrylamide), and the superhydrophobic surface is prepared by spraying a mixture of titanium dioxide and fluoride ST-110.

[0063] The power generation interlayer contains droplet power generation units, in contrast. Figure 2 , Figure 3 and Figure 4 The droplet power generation unit can include multiple power generation modules arranged sequentially. Each power generation module includes an FEP-double-sided conductive cloth adhesive layer 17 (made by bonding double-sided conductive cloth to an ethylene propylene oxide film FEP), a main support frame 16, and an aluminum electrode plate 14. The left and right ends of the main support frame 16 are set on the inner wall of the power generation interlayer 10, and the main support frame 16 is inclined downward. The surface of the main support frame 16 is provided with the FEP-double-sided conductive cloth adhesive layer 17 to form the main body of the power generation surface. The bottom surface of the main body of the power generation surface is provided with an aluminum electrode plate 14 (i.e., an aluminum sheet). The aluminum electrode plate 14 and the top of the main body of the power generation surface are respectively connected to the power source 9 through wires. Among them, the double-sided conductive cloth is bonded to the FEP film, and the thickness of the conductive area cloth is equal to the thickness of the FEP film, with a thickness of 100-300μm. The thickness of the aluminum electrode plate 14 is 80μm, and the surface inclination is 0-60°. The distance between the power generation surface and the patterned superhydrophobic / thermal responsive superwetting droplet separation membrane is 5-50cm. The top of the power generation interlayer is connected to the oil-water separation interlayer, and the bottom is connected to the one-way liquid chamber. All connections are made via flanges and sealed with sealing rings. The droplet power generation surface technology used in this embodiment is a mature existing technology; for example, see the document "A Single-Droplet Electricity Generator Achieves an Ultrahigh Output Over100 V Without Pre-Charging".

[0064] The droplet power generation surface is mainly composed of an ethylene propylene oxide film (FEP), a double-sided conductive cloth and an aluminum sheet. When the water droplet contacts the solid surface, it begins to spread on the solid surface around the falling point, and the contact area of the solid-liquid interface gradually increases. After the contact area reaches its maximum value, the droplet begins to shrink with the decrease of the contact area, and the physical shape of the droplet is constantly changing. Finally, due to surface tension, the dispersed droplets gather together and slide down through the aluminum sheet surface. The droplet can form a capacitance with the surface by using contact electrification and electrostatic induction during the movement of the droplet on the surface, and the droplet forms a droplet-FEP capacitance (C D / F ), a droplet-aluminum sheet capacitance (C D / A ), a FEP-conductive cloth capacitance (C F / C ) and a conductive cloth-aluminum sheet capacitance (C C / A ) when the droplet moves to different positions on the surface, and the charges carried in each capacitance will be charged and discharged between different capacitors with the movement of the droplet, further forming an electric current to power the external power supply. The power generation surface has a thickness of 100-300 μm, the aluminum sheet has a thickness of about 80 μm, the surface inclination is 0-60°, and the distance between the power generation surface and the heat-responsive dual-wettability separation film is 5-50 cm.

[0065] The top of the single-phase liquid cavity is connected to the bottom of the power generation sandwich layer through a flange, and is sealed by a sealing ring. The liquid outlet is connected to the external pipeline through a liquid outlet valve.

[0066] 1. Processing of heat-responsive super-wetting separation film:

[0067] The required materials include methanol, ethanol, 200-325 mesh metal mesh, chloroform, methyl methacrylate (MMA), dimethylformamide (DMF), N2H4·H2O, N-isopropyl acrylamide (NIPAAm), hexamethyl triamine (2-aminoethyl) amine (Me6-TREN), ethyl bromoisobutyrate (Eib-Br), aluminum oxide column, 75 μm red copper powder, carboxylated carbon nanotube.

[0068] Synthesis of macromolecular initiator PMMA-Br: 5 mL of methyl methacrylate (MMA), 5 mL of dimethylformamide (DMF), 15 mg of red copper powder, 11.2 μL of N2H4·H2O, 61.1 μL of hexamethyl triamine (2-aminoethyl) amine (Me6-TREN) were placed in a lenk bottle and stirred for 15 min, then 34.4 μL of ethyl bromoisobutyrate (Eib-Br) was added, and the polymerization reaction was carried out at 90°C. Dilute the reaction mixture with chloroform, and remove the catalyst by passing through an alumina column. Finally, the concentrated solution is repeatedly poured into methanol, and dried under vacuum at 40°C to obtain the macroinitiator PMMA-Br.

[0069] Synthesis of copolymer PMMA-b-PNIPAAm solution: 300 mg of PMMA-Br, 3 mL of DMF / 2-propanol mixed solvent (volume ratio of 2 / 1), 1.6 mg of red copper powder, 1.2 μL of N2H4·H2O and 7.5 μL of Me6TREN, and 12 mg of carboxylated carbon nanotubes were placed in a 25 mL length flask and stirred for 5 min. Then, 565 mg of NIPAAm was dissolved in 1 mL of DMF / 2-propanol mixed solution (volume ratio of 2 / 1) and polymerized at 50°C. After removing the catalyst, the PMMA-b-NIPAAm block copolymer was repeatedly precipitated from anhydrous ether and dried under vacuum at 40°C.

[0070] The metal mesh was treated with acetone and ethanol in series for 30 min with ultrasonic treatment, and dried with nitrogen flow. The rinsed metal mesh was cut into a circle as the substrate for subsequent smart membrane preparation.

[0071] Preparation of PMMA-b-PNIPAAm fiber membrane by electrospinning method: PMMA-b-PNIPAAm was dissolved in a mixed solvent of DMF / chloroform with a volume ratio of 1 / 2, and the concentration of PMMA-b-PNIPAAm was 25 wt%. After stirring for 24 h, the prepared solution was electrospun in a closed chamber. During the electrospinning process, the applied voltage was maintained at about 14 kV, and the solution feeding rate was set to 0.2 mL / h by an injection pump. The as-spun fibers were collected with a pre-cleaned circular metal mesh, and the obtained fiber membrane was dried at 50°C for 12 hours to remove any residual solvent.

[0072] 2. Processing of patterned superamphiphobic / thermo-responsive super- wetting droplet separation membrane:

[0073] The patterned surface was mainly prepared by spraying a fluorine-titanium dioxide suspension solution on the basis of the thermo-responsive super-wetting separation membrane through a mask method. The mask was a circle with a diameter of 1-3 mm and a spacing of 1-2 mm.

[0074] The specific preparation method is as follows:

[0075] The required materials include titanium dioxide, anhydrous ethanol, ST-110, deionized water, etc., which are purchased from the National Pharmaceutical Group Chemical Reagent Co., Ltd., and the reagent purity is analytical grade. 304 stainless steel mesh is used as the substrate, and the thickness of the substrate is 0.1 mm and the diameter is 15 cm.

[0076] 1 g of titanium dioxide was mixed with 30 g of anhydrous ethanol to obtain a mixed solution A; the mixed solution A was ultrasonically treated for 1 hour to make the titanium dioxide completely dispersed; then, 900 μL of ST-110 was added to the mixed solution A, and fast stirring was performed with a magnetic stirrer to obtain a mixed solution B; then, the mixed solution B was allowed to react at room temperature for 6 h. The fluoride-titanium dioxide suspension solution was prepared by hydrolysis and condensation of titanium dioxide and ST-110, in which the titanium dioxide was the solute, and the solvent was anhydrous ethanol.

[0077] Then, the mixed solution B of the fluoride-titanium dioxide suspension solution and ST-110 was sprayed onto a 304 stainless steel substrate under a mask condition using a spray pen at a N2 pressure of 0.5 MPa, and the spraying time was 60 s, to prepare a super-biphobic coating, which had a water droplet contact angle of 150 degrees and a hysteresis angle of 5 degrees in air. The super-biphobic coating had an oil droplet contact angle of 150 degrees and a hysteresis angle of 5 degrees in air. Thus, the super-biphobic coating had good hydrophobic / oil-repellent properties. The thickness of the super-biphobic coating was 100 μm.

[0078] During the spraying process, the 304 stainless steel mesh substrate was fixed on a hot plate with a temperature of 100 ℃ to accelerate the evaporation of the solvent. The titanium dioxide formed a micro-nano structure on the surface of the stainless steel mesh substrate.

[0079] The titanium dioxide and fluoride on the surface of the 304 stainless steel mesh substrate made the surface have a low surface energy. Due to the high content of fluorine elements in the super-hydrophobic / super-oil-repellent coating, the super-hydrophobic / super-oil-repellent coating had a low surface energy, and had super-repellent properties to organic solvents and water with low surface tension coefficients.

[0080] 3. Processing of the surface of the liquid droplet power generation unit body:

[0081] The required materials included an ethylene propylene oxide film (FEP), a double-sided conductive cloth, an aluminum sheet, deionized water, a plastic substrate mold, and a wire.

[0082] Preparation: The FEP film (100 microns) with strong electron-withdrawing ability was used as a solid contact surface. First, the FEP film was cleaned with deionized water and dried in an infrared oven at 60 ℃. In order to process the sensing electrode on the back of the FEP, we directly pasted the double-sided conductive cloth on the FEP film. The thickness of the conductive area cloth was equal to the thickness of the FEP film, which was 100 μm. In order to construct the aluminum on the DEG, a square aluminum strip was cut and processed by laser, and the thickness of the aluminum strip was 80 microns, which was then assembled onto the FEP film. Finally, the plastic substrate mold was made by a 3D printing method, and the finished SEDEG device was connected with wires and fixed on the mold substrate.

[0083] A separation method of an oil-water separation device based on spontaneous electricity control and electrically heated switchable wettability surface, when the separation object is light oil-water mixture, the separation steps are as follows:

[0084] 1) open the exhaust valve at the top of the multi-phase oil-water chamber 6;

[0085] 2) open the front end communication valve of the residue filter 3;

[0086] 3) under the action of gravity, the light oil-water mixture first enters the residue filter 3 to separate the solid impurities contained in the mixture;

[0087] 4) the light oil-water mixture enters the multi-phase oil-water chamber 6, and after the light oil-water mixture is passed through, the front end communication valve of the residue filter is closed;

[0088] 5) the light oil-water mixture contacts the patterned super-amphiphobic / thermally responsive super-wetting droplet separation membrane in the separation layer 8, the surface of the patterned super-amphiphobic / thermally responsive super-wetting droplet separation membrane is a super-amphiphobic / air super-hydrophilic-underwater super-oleophobic patterned surface at room temperature, and since the water in the mixture is in the lower layer, it directly penetrates the patterned super-amphiphobic / thermally responsive super-wetting droplet separation membrane, while the light oil cannot penetrate the patterned super-amphiphobic / thermally responsive super-wetting droplet separation membrane, realizing the separation of the light oil-water mixture;

[0089] 6) the separated water droplets fall onto the liquid droplet power generation unit surface of the power generation layer 10, converting the potential energy of the water droplets into electrical energy to charge the power supply outside the power generation layer 10;

[0090] 7) as the water in the multi-phase oil-water chamber 6 is completely separated, open the liquid outlet valve at the bottom of the single-phase liquid chamber 13 to completely discharge the separated water, and then close the liquid outlet valve;

[0091] 8) finally, turn on the power switch outside the separation layer 8 to heat the patterned super-amphiphobic / thermally responsive super-wetting droplet separation membrane, so that the separation membrane changes from a super-amphiphobic / air super-hydrophilic-underwater super-oleophobic patterned surface to a super-amphiphobic / air hydrophobic-underwater oleophilic patterned surface, so that the remaining oil phase in the multi-phase oil-water chamber penetrates the separation membrane and enters the single-phase liquid chamber and is discharged.

[0092] A separation method of an oil-water separation device based on spontaneous electricity control and electrically heated switchable wettability surface, when the separation object is heavy oil-water mixture, the separation steps are as follows:

[0093] 1) turn on the power switch outside the separation layer 8 to heat the patterned super-amphiphobic / thermally responsive super-wetting droplet separation membrane, so that the separation membrane changes from a super-amphiphobic / air super-hydrophilic-underwater super-oleophobic patterned surface to a super-amphiphobic / air hydrophobic-underwater oleophilic patterned surface;

[0094] 2) open the exhaust valve at the top of the multi-phase oil-water chamber 6;

[0095] 3) open the front end communication valve of the filter 3;

[0096] 4) under the action of gravity, the heavy oil-water mixture first enters the filter 3 to separate the solid impurities contained in the mixture;

[0097] 5) the heavy oil-water mixture enters the multi-phase oil-water cavity 6, and after the heavy oil-water mixture is completely introduced, the front end communication valve of the filter is closed;

[0098] 6) the heavy oil-water mixture contacts the patterned super-amphiphobic / thermally responsive super-wetting droplet separation membrane in the separation interlayer 8, and under the heating condition, the surface of the separation membrane is a super-amphiphobic / air hydrophobic-water oleophilic patterned surface, so the heavy oil in the mixture directly penetrates the separation membrane, while the water cannot penetrate the separation membrane, thereby realizing the separation of the heavy oil-water mixture;

[0099] 7) open the liquid outlet valve of the liquid outlet at the bottom of the single-phase liquid cavity 13 to completely discharge the separated heavy oil, and then close the liquid outlet valve of the liquid outlet;

[0100] 8) finally, the power switch outside the separation interlayer 8 is closed, the separation membrane changes from a super-amphiphobic / air hydrophobic-water oleophilic patterned surface to a super-amphiphobic / air super-hydrophilic-water super-oleophobic patterned surface, so that the remaining water phase in the multi-phase oil-water cavity penetrates the separation membrane and enters the single-phase liquid cavity and is discharged.

[0101] When the present application separates light oil-water with a separation quality ratio of 1:1, the separation flux is controlled at 18-25 L·m -2 ·s -1 Under the condition that the separation efficiency of water can reach more than 98%, the COD value of the water phase after separation can be maintained below 300 mg / L, achieving a very good separation effect. Moreover, by using the method of the present application, the power generation capacity of the power generation interlayer can meet the power consumption of the oil-water separation interlayer.

[0102] The content described in the specification is only a list of implementation forms of the inventive concept, and the protection scope of the present application should not be regarded as limited to the specific forms stated in the embodiments.

Claims

1. An oil-water separation device based on self-generated power control and electrothermal switching wettability surface, characterized in that... The system includes a connecting valve (2), a filter (3), and an oil-water separator connected in sequence by pipelines. The oil-water separator includes, from top to bottom, a multiphase oil-water chamber (6), a separation jacket (8), a power generation jacket (10), and a single-phase liquid chamber (13). The top of the multiphase oil-water chamber (6) is equipped with an exhaust valve (5) and a pressure gauge (4); the bottom of the single-phase liquid chamber (13) is equipped with a liquid outlet (11) and a liquid outlet valve (12). The separation interlayer (8) contains a patterned superhydrophobic / thermally responsive superwetting droplet separation membrane. It is based on a porous metal mesh. The patterned surface coating of the substrate is composed of a thermally responsive superwetting separation membrane material (19) and a superhydrophobic material (20). When the temperature of the surface of the porous metal mesh substrate is changed under the condition of being energized, the wettability of the separation membrane material to oil and water can be changed, thereby achieving selective separation of oil-water mixture. The separation interlayer (8) is provided with a power switch (7) on the outside and a power source (9) is provided on the outer side wall of the power generation interlayer (10). The power generation interlayer (10) contains a droplet power generation unit. The droplet power generation unit is connected to the power source (9) through a wire. The water droplets separated by the separation interlayer (8) hit the surface of the droplet power generation unit to generate charges, thereby realizing the conversion of the gravitational potential energy of the droplets into electrical energy. The converted electrical energy can be stored in the power source (9). The power source (9) is connected to the porous metal mesh substrate of the patterned superhydrophobic / thermal responsive superwetting droplet separation membrane through a wire and a power switch (7). It can supply power to the porous metal mesh substrate so as to realize the efficient oil-water separation process of the electrothermal switching wettability surface controlled by self-generated power. A thermally responsive superwetting separation membrane material (19) with multiple circular coatings arranged in an array on the surface of the substrate is a superhydrophobic material (20). The process for preparing the thermally responsive superwetting separation membrane material (19) on the surface of the porous metal mesh substrate is as follows: 1) Preparation of copolymer poly(methyl methacrylate)-block poly(n-isopropylacrylamide): Initiator PMMA-Br, copper powder, N2H4·H2O, Me6TREN and carboxylated carbon nanotubes were added to organic solvent A. After stirring for 2-10 min, N-isopropylacrylamide NIPAAm was added, and the polymerization reaction was carried out at 40-70℃. After the reaction was completed, the catalyst was removed, and the polymerization product was repeatedly precipitated from anhydrous diethyl ether and dried to obtain copolymer poly(methyl methacrylate)-block poly(n-isopropylacrylamide), which is PMMA-b-NIPAAm block copolymer. 2) Preparation of PMMA-b-PNIPAAm fiber membrane by electrospinning: The PMMA-b-NIPAAm block copolymer is dissolved in organic solvent B and stirred for 10-40 h. The prepared solution is then electrospun in a closed chamber. During the electrospinning process, the applied voltage is maintained at 10-20 kV. The original spun fibers are collected using a circular porous metal mesh. The obtained fiber membrane is then dried to remove residual solvent, thus completing the preparation.

2. The oil-water separation device based on self-generated power control and electrothermal switching wettability surface as described in claim 1, characterized in that... The coating thickness of the thermally responsive superwetting separation membrane material (19) is 100-150 μm; the thermally responsive superwetting separation membrane material (19) is a temperature-sensitive material that can reversibly change the surface between two states of air superhydrophilic-underwater superoleophobic and air superhydrophobic-underwater superoleophilic under temperature change, with a transition temperature of 30-35℃; the superhydrophobic material (20) maintains a superhydrophobic state under changing temperature conditions.

3. The oil-water separation device based on self-generated power control and electrothermal switching wettability surface as described in claim 1, characterized in that... In step 1), the feed ratio of the initiator PMMA-Br, copper powder, N2H4·H2O, Me6TREN and carboxylated carbon nanotubes is 200-400mg: 1-2mg: 1-1.5μL: 5-10μL: 10-15mg.

4. The oil-water separation device based on self-generated power control and electrothermal switching wettability surface as described in claim 3, characterized in that... In step 1), the feed ratio of the initiator PMMA-Br, copper powder, N2H4·H2O, Me6TREN and carboxylated carbon nanotubes is 300mg: 1.5-1.6mg: 1.1-1.2μL: 7-7.5μL: 10-12mg.

5. The oil-water separation device based on self-generated power control and electrothermal switching wettability surface as described in claim 1, characterized in that... In step 1), the organic solvent A is a DMF / 2-propanol mixed solvent with a volume ratio of 1 to 4:1; in step 2), the organic solvent B is a DMF / chloroform mixed solvent with a volume ratio of 1 to 4, and the mass concentration of PMMA-b-NIPAAm in the organic solvent is 20-25%.

6. The oil-water separation device based on self-generated power control and electrothermal switching wettability surface as described in claim 5, characterized in that... In step 1), the organic solvent A is a DMF / 2-propanol mixed solvent with a volume ratio of 2:1; in step 2), the organic solvent B is a DMF / chloroform mixed solvent with a volume ratio of 1:

2.

7. The oil-water separation device based on self-generated power control and electrothermal switching wettability surface as described in claim 1, characterized in that... The circular coatings arranged in an array on the surface of the porous metal mesh substrate, which serve as thermally responsive superwetting separation membrane materials, have a diameter of 1-3 mm and an adjacent spacing of 1-2 mm.

8. The oil-water separation device based on self-generated power control and electrothermal switching wettability surface as described in claim 1, characterized in that... The superhydrophobic material (20) includes titanium dioxide and fluoride ST-110, and the feeding ratio of the two is 1g: 0.8~1.2mL; The preparation method of the superhydrophobic material (20) on the porous metal mesh substrate surface is as follows: after preparing a thermally responsive superwetting separation membrane material (19) on the porous metal mesh substrate surface, a fluoride-titanium dioxide suspension solution is sprayed onto the thermally responsive superwetting separation membrane material by a masking method. The mask is circular with a diameter of 1-3 mm and a spacing of 1-2 mm. The specific preparation process is as follows: S1: Add titanium dioxide to anhydrous ethanol and disperse it by ultrasonication. Then add fluoride ST-110, stir evenly, and react at room temperature for 5-7 hours. Prepare fluoride-titanium dioxide suspension through hydrolysis and condensation of titanium dioxide and ST-110. S2: A mask is applied to a thermally responsive superwetting separation membrane material (19) on the surface of a porous metal mesh substrate, and then a fluoride-titanium dioxide suspension is sprayed onto its surface using an airbrush to prepare a superhydrophobic coating. The superhydrophobic coating has a water droplet contact angle of 145-155° and a hysteresis angle of 4-6° in air, and an oil droplet contact angle of 145-155° and a hysteresis angle of 4-6° in air. The thickness of the superhydrophobic coating is 80-150 μm.

9. The separation method of an oil-water separation device based on self-generated power control and electrothermal switching wettability surface as described in claim 1, characterized in that... When the object to be separated is a light oil-water mixture, the separation steps are as follows: 1) Open the top vent valve of the multiphase oil-water chamber (6); 2) Open the front connecting valve of the filter (3); 3) Under the action of gravity, the light oil-water mixture first enters the filter (3) to separate the solid impurities contained in the mixture; 4) The light oil-water mixture enters the multiphase oil-water chamber (6). After the light oil-water mixture is introduced, the connecting valve at the front end of the filter is closed. 5) The patterned superhydrophobic / thermal responsive superwetting droplet separation membrane in the light oil-water mixture contact separation interlayer (8) has a superhydrophobic / air-superhydrophilic-underwater superoleophobic patterned surface at room temperature. Since the water in the mixture is in the lower layer, it can directly pass through the patterned superhydrophobic / thermal responsive superwetting droplet separation membrane, while the light oil cannot pass through the patterned superhydrophobic / thermal responsive superwetting droplet separation membrane, thus achieving the separation of the light oil-water mixture. 6) The separated water droplets fall onto the surface of the droplet power generation unit of the power generation interlayer (10), converting the potential energy of the water droplets into electrical energy to charge the external power source of the power generation interlayer (10). 7) As the water in the multiphase oil-water chamber (6) is completely separated, open the outlet valve at the bottom of the single-phase liquid chamber (13) to completely drain the separated water, and then close the outlet valve. 8) Finally, turn on the power switch outside the separation jacket (8) to heat the patterned superhydrophobic / thermal responsive superwetting droplet separation membrane, so that the separation membrane changes from a superhydrophobic / air superhydrophilic-underwater superoleophobic patterned surface to a superhydrophobic / air hydrophobic-underwater oleophilic patterned surface, so that the remaining oil phase in the multiphase oil-water cavity passes through the separation membrane, enters the single-phase liquid cavity and is discharged.

10. The separation method of an oil-water separation device based on self-generated power control and electrothermal switching wettability surface as described in claim 1, characterized in that... When the object to be separated is a heavy oil-water mixture, the separation steps are as follows: 1) Turn on the power switch on the outside of the separation jacket (8) to heat the patterned super-amphihydrophobic / thermal-responsive superwetting droplet separation membrane, so that the separation membrane changes from the super-amphihydrophobic / air superhydrophilic-underwater superoleophobic patterned surface to the super-amphihydrophobic / air hydrophobic-underwater oleophilic patterned surface. 2) Open the top vent valve of the multiphase oil-water chamber (6); 3) Open the front connecting valve of the filter (3); 4) Under the action of gravity, the heavy oil-water mixture first enters the filter (3) to separate the solid impurities contained in the mixture; 5) The heavy oil-water mixture enters the multiphase oil-water chamber (6). After the heavy oil-water mixture is introduced, the front-end connecting valve of the filter is closed. 6) The patterned superhydrophobic / thermally responsive superwetting droplet separation membrane in the heavy oil-water mixture contact separation jacket (8) has a superhydrophobic / air hydrophobic-water underwater oleophilic patterned surface under heating conditions. Since the heavy oil in the mixture is in the lower layer, it can directly pass through the separation membrane, while the water cannot pass through the separation membrane, thus achieving the separation of heavy oil-water mixture. 7) Open the outlet valve at the bottom of the single-phase liquid chamber (13) to completely discharge the separated heavy oil, and then close the outlet valve. 8) Finally, turn off the power switch outside the separation jacket (8). The separation membrane changes from a super-amphihydrophobic / air-hydrophobic-underwater oleophilic patterned surface to a super-amphihydrophobic / air-superhydrophilic-underwater superoleophobic patterned surface, so that the remaining water phase in the multiphase oil-water cavity passes through the separation membrane, enters the single-phase liquid cavity and is discharged.

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