Inductively coupled plasma spraying method for preparing oil-water separation membrane

Abstract

The invention discloses an inductively coupled plasma spraying preparation method for an oil-water separation mesh membrane, which specifically relates to the technical field of functional materials, and comprises the following steps: step 1: using anhydrous ethanol to clean the metal mesh to remove organic attachments on its surface, then using compressed air to blow dry and fix it on a fixture; step 2: starting the inductively coupled plasma generator, and using a pure plasma flame flow to quickly scan the metal mesh for preheating without any raw material injection; step 3: after the preheating is completed, using a precursor solution of ytterbium oxide as a spraying raw material to inject into the plasma flame flow, and after the flame flow is stable, spraying the surface of the metal mesh. The invention innovatively uses an inductively coupled plasma spraying process to deposit a rare earth oxide film on a metal mesh to achieve the preparation of a super-hydrophobic / super-oleophilic mesh membrane.

Description

Technical Field

[0001] The invention relates to the technical field of functional materials, and in particular to an inductively coupled plasma spraying preparation method for an oil-water separation membrane. Background Art

[0002] With the rapid development of social economy, oil has become an increasingly important industrial resource. The extraction, transportation and smelting of oil are the cornerstone industries of industrial production. In important industries such as oil production, development and processing, the discharge of oily wastewater often occurs, and sometimes it is accompanied by serious accidents such as oil spills, resulting in serious oil waste and environmental pollution. Oil-water separation technology is an effective way to solve the discharge of oily wastewater and oil spills. Currently, commonly used oil-water separation technologies include flotation treatment, physical / chemical adsorption, combustion, biological treatment, etc. These methods can achieve oil-water separation to a certain extent. However, the process has problems such as complex operation, low efficiency, high cost and secondary pollution.

[0003] With the development of materials science and bionics, the study of the wettability of solid surfaces has made great progress. Now, a variety of surfaces with obvious wettability differences for different liquids have been developed. Among them, surfaces that show obvious wettability differences for oil and water can be used for oil-water separation operations. The most representative of these is the super-hydrophobic / super-oleophilic mesh prepared with a metal mesh as the matrix. The mesh has extremely high hydrophobicity and extremely high oleophilicity. When the oil-water mixture passes through the mesh, the water is intercepted by the mesh and the oil can pass through, thereby achieving oil-water separation. Its oil-water separation process is simple to operate, the mesh is reusable and has a high separation efficiency, and has become an important method for oil-water separation. To use the super-hydrophobic / super-oleophilic mesh for oil-water separation operations, the mesh must first be prepared. However, the existing super-hydrophobic / super-oleophilic mesh preparation process faces the limitations of cumbersome and complex preparation processes, a wide variety of raw materials required, low preparation efficiency, and long preparation time. Many preparation links also need to be carried out in constant temperature or constant pressure equipment, which seriously limits the preparation area of ​​the oil-water separation mesh. For example, Chinese patent CN201610396879.5 describes a method for preparing an oil-water separation network by mixing ZrOCl 2 8H 2 O solution, hydrofluoric acid and C 6 H 5 PO(OH) 2The solution is mixed in a certain proportion to prepare a zirconium phenylphosphonate reaction solution, and then the copper mesh and the zirconium phenylphosphonate reaction solution are placed in a reactor, and a constant temperature of 100-130 degrees Celsius is maintained. After 1.5-2.5 hours of reaction, a super-hydrophobic / super-oleophilic copper mesh can be obtained. The preparation method described in the patent needs to maintain a constant temperature, a long preparation time, and the preparation size is limited by the size of the reactor. Chinese patent CN201210152727.2 describes a kind of oil-water separation mesh and a preparation method thereof, which is to mix polylactic acid, an organic solvent, and a sealing agent in a certain proportion to obtain a mixed solution, spread the mixed solution on the surface of the substrate and let it stand for 3 minutes, then immerse the substrate in anhydrous ethanol for phase separation for 30 minutes to form a film, and then immerse the substrate with the film in water for 10 hours, then take it out and put it into a 40 degree Celsius constant temperature oven for drying, and the oil-water separation mesh can be obtained. The preparation process described in the patent is very time-consuming, the preparation rate is low, and the sample preparation size is limited by the internal size of the oven. Asif Matin et al. describe a method for preparing a super-hydrophobic / super-oleophilic oil-water separation screen in article [Facile fabrication of superhydrophobic / superoleophilic microporousmembranes by spray-coating ytterbium oxide particles for efficient oil-waterseparation.Journal of Membrane Science 548(2018):390-397.], it is to add ytterbium oxide particles to tetrahydrofuran to obtain a mixed solution, the mixed solution is subjected to magnetic stirring for 24-72 hours and an ultrasonic water bath for 1-2 hours, and then the mixed solution is sprayed on a stainless steel screen with a high-pressure air spraying process, the stainless steel screen after spraying is placed in the air to dry, and then placed in a high-temperature furnace at 200 degrees Celsius for heat preservation treatment, and the stainless steel screen of super-hydrophobic / super-oleophilic can be obtained. The preparation process described in the article is very time-consuming, and a high-temperature furnace heat preservation treatment is required, and the sample size is limited by the internal space of the high-temperature furnace. In addition, many superhydrophobic / superoleophilic membranes are prepared using organic polymer materials, which have low mechanical strength and are easily destroyed, decomposed and deteriorated under high temperature conditions, resulting in reduced or lost hydrophobicity, making it impossible to achieve oil-water separation operations.

[0004] The article [Hydrophobicity of rare-earth oxide ceramics. Nature materials 12 (2013): 315-320.] reports that lanthanide rare earth oxides have intrinsic hydrophobicity. As ceramic materials, rare earth oxides have high hardness, high temperature resistance, corrosion resistance and stable chemical properties, which provides great inspiration for the present invention, that is, through the development of new processes to achieve rapid, efficient and large-area preparation of super-hydrophobic / super-oleophilic rare earth oxide mesh membranes, improve the mechanical properties and thermal stability of the mesh membranes, solve the main problems of existing super-hydrophobic / super-oleophilic mesh membranes in preparation and application, and have important economic value and engineering significance. Summary of the invention

[0005] In view of the limitations of the super-hydrophobic / super-oleophilic mesh preparation process in the prior art, the present application provides an inductively coupled plasma spraying preparation method for an oil-water separation mesh, which is a process for preparing a super-hydrophobic / super-oleophilic mesh using an inductively coupled plasma (ICP) spraying process. The process is flexible and convenient to prepare, has a high preparation rate, and can achieve one-step preparation of a micro-nano binary structure coating on a metal wire mesh with extremely low consumption of spraying raw materials.

[0006] The inductively coupled plasma spraying preparation method of the oil-water separation mesh membrane is characterized by comprising the following steps:

[0007] Step 1: Use anhydrous ethanol to clean the metal mesh to remove organic attachments on its surface, then use compressed air to blow it dry and fix it on the fixture;

[0008] Step 2: Start the inductively coupled plasma generator and use the pure plasma flame to quickly scan the metal wire mesh for preheating without any raw material injection;

[0009] Step 3: After preheating, the precursor solution of ytterbium oxide is injected into the plasma flame flow as the spraying material, and after the flame flow is stabilized, the surface of the metal wire mesh is sprayed.

[0010] Furthermore, the precursor solution of ytterbium oxide is ytterbium nitrate solution or ytterbium sulfate solution.

[0011] Furthermore, the ytterbium nitrate is easily a solution prepared with ytterbium nitrate as solute and anhydrous ethanol and / or distilled water as solvent; the ytterbium sulfate solution is a solution prepared with ytterbium sulfate as solute and anhydrous ethanol and / or distilled water as solvent.

[0012] Furthermore, the metal wire mesh is made of stainless steel wire mesh, brass wire mesh or nickel-based alloy wire mesh.

[0013] Furthermore, the inductively coupled plasma generator includes a torch tube, and in step 3, the moving path of the torch tube is a "bow-shaped" path.

[0014] Furthermore, the mesh film formed in step 3 is a rare earth oxide film.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention innovatively uses an inductively coupled plasma spraying process to deposit a rare earth oxide film on a metal wire mesh to achieve the preparation of a super-hydrophobic / super-oleophilic mesh. Compared with other preparation techniques, the process is flexible, convenient, efficient and fast, and can achieve a one-step rapid preparation of a super-hydrophobic / super-oleophilic mesh with extremely low raw material consumption, and the spraying area is not limited, and large-area preparation can be achieved. In addition, the material of the mesh is a rare earth oxide ceramic material, which has higher mechanical strength and thermal stability than the organic polymer material in other preparation techniques. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of inductively coupled plasma spraying;

[0018] Figure 2 Front view of wire mesh

[0019] Figure 3 Schematic diagram of the single-layer scanning path of the flame flow on the metal wire mesh

[0020] Figure 4 This is an electron microscope picture of the stainless steel wire mesh;

[0021] Figure 5 Electron microscope pictures of the metal mesh after spraying in Example 1 at different magnifications;

[0022] Figure 6 The water contact angle of the metal mesh after spraying in Example 1;

[0023] Figure 7 The oil contact angle of the metal mesh after spraying in Example 1;

[0024] Figure 8 Electron microscope pictures of the metal mesh after spraying in Example 2 at different magnifications;

[0025] Fig. 9 The water contact angle of the metal mesh after spraying in Example 2;

[0026] Fig.10 This is the oil contact angle of the metal mesh after spraying in Example 2.

[0027] In the figure: 1. Precursor solution; 2. Metal mesh; 3. Gas supply system; 4. High frequency generator; 5. Torch; 6. Peristaltic pump; 7. Atomizing nozzle; 8. Flame flow; 9. Atomized solution; 10. Induction coil. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0029] like Figure 1 As shown, the inductively coupled plasma device mainly includes a gas supply system 3, a high-frequency generator 4, a torch tube 5 and a feeding system. Among them, the torch tube 5 is a standard Fassel-type torch tube composed of three layers of coaxial quartz tubes, and an induction coil 10 surrounds the front end of the torch tube 5. The high-frequency generator 4 generates a high-frequency current through the induction coil 10, ionizing the gas entering the torch tube 5 to form a plasma flame flow 8; the gas supply system 3 respectively feeds gas into the middle layer and the outer layer of the torch tube 5, and the middle layer gas will be ionized to generate a plasma flame flow 8, while the outer layer gas plays a cooling role, so that the torch tube 5 is protected from the ablation of the high-temperature plasma flame flow 8. The middle layer gas and the outer layer gas are usually argon, but the flow rates of the two are greatly different due to their different functions, and the outer layer gas flow rate is much larger than the middle layer gas flow rate. The feeding system mainly includes a peristaltic pump 6 and an atomizing nozzle 7. One end of the peristaltic pump 6 is connected to the precursor solution 1 of ytterbium oxide, and the other end of the peristaltic pump 6 is connected to the atomizing nozzle 7. Atomizing gas is introduced between the peristaltic pump 6 and the atomizing nozzle 7 to form an atomized solution 9 at the ejection end of the atomizing nozzle 7 and input to the innermost layer of the torch tube 5. After the atomized solution 9 is input into the torch tube 5, it is heated and accelerated in the plasma flame flow 8, and after a series of thermochemical and thermophysical changes, tiny ytterbium oxide particles are formed, which are deposited on the metal wire mesh 2 to form a coating.

[0030] The inductively coupled plasma spraying preparation method of the oil-water separation mesh membrane of the present invention comprises the following steps:

[0031] Step 1: Use anhydrous ethanol to clean the metal mesh to remove organic attachments on its surface, then use compressed air to blow it dry and fix it on the fixture;

[0032] There are many types of metal meshes, and stainless steel mesh, brass mesh, nickel-based mesh, etc. are preferably used. The mesh size is preferably 80-200 meshes. Before spraying, first use anhydrous ethanol to clean the surface of the metal mesh to remove organic attachments on the surface, and then use compressed air to blow dry. After drying, fix the metal mesh on the fixture.

[0033] Step 2: Start the inductively coupled plasma generator and use the pure plasma flame to quickly scan the metal wire mesh for preheating without any raw material injection;

[0034] Specifically, the gas supply system 3 is started and the gas supply volume is adjusted so that the outer layer gas of the torch tube 5 is argon gas with a flow rate of 10-20 liters per minute, and the middle layer gas of the torch tube 5 is argon gas with a flow rate of 0.5-2 liters per minute; the high frequency generator 4 is started, and the plasma power is adjusted to be stable at 1-2 kilowatts; the inductively coupled plasma device is driven by a mechanical arm to move, and the metal wire mesh 2 is preheated by scanning the flame flow 8 without injecting a solution, and the moving path of the torch tube 5 relative to the metal wire mesh 2 is a bow-shaped path, specifically as follows Figure 3 As shown, the moving speed is 200-500 mm per minute and the track spacing is 2.5-4 mm.

[0035] Step 3: After preheating, the precursor solution of ytterbium oxide is injected into the plasma flame flow as the spraying material, and after the flame flow is stabilized, the surface of the metal wire mesh is sprayed.

[0036] Among them, the precursor solution of ytterbium oxide is preferably ytterbium nitrate solution or ytterbium sulfate solution. The preparation method thereof is described by taking ytterbium nitrate solution as an example: ytterbium nitrate is used as solute and anhydrous ethanol is used as solvent to prepare a solution of the required concentration. Of course, the solvent can also be distilled water or a mixture of the two. It should be noted that the concentration of the ytterbium nitrate solution can be adjusted as needed.

[0037] After the preheating of the metal mesh 2 is completed, the atomizing gas is input, and the atomized solution 9 is injected into the innermost layer of the torch tube 5 through the peristaltic pump 6 and the atomizing nozzle 7, wherein the atomizing gas is argon gas with a flow rate of 0.5-1 liter per minute; the outer layer gas is argon gas with a flow rate of 10-20 liters per minute; the middle layer gas is argon gas with a flow rate of 0.5-2 liters per minute; the concentration of the ytterbium oxide precursor solution 1 is 1-2.5 mol per liter, and the ytterbium oxide precursor solution 1 is atomized by argon gas with a flow rate of 0.5-1.5 liters per minute, and then injected into the innermost layer of the torch tube 5 through a nozzle with an inner diameter of 0.5-2.5 mm, and the liquid delivery volume is 30-100 microliters per minute; the distance between the outlet of the torch tube 5 and the metal mesh 2 is 60-100 mm. After the plasma flame flow 8 is stabilized, the inductively coupled plasma device is moved by the robot arm to spray the metal mesh 2, and the torch tube 5 is arranged according to Figure 3 The "bow-shaped" path shown is moved to achieve full coverage spraying of the metal mesh 2. The moving speed of the metal mesh 2 relative to the torch tube 5 is 200-500 mm per second, and the number of spray layers is 20-50 layers.

[0038] The present invention combines inductively coupled plasma spraying process with lanthanide rare earth oxide and is applied to the preparation of oil-water separation mesh membrane, and uses inductively coupled plasma spraying process to deposit rare earth oxide film on metal wire mesh, and realizes the preparation of super hydrophobic / super oleophilic mesh membrane. Compared with other preparation technologies, this technological process is flexible and convenient, efficient and fast, and can realize the one-step rapid preparation of super hydrophobic / super oleophilic mesh membrane when raw material consumption is extremely low, and the spraying area is not limited, and large-scale preparation can be realized. In addition, the material of the mesh membrane is rare earth oxide ceramic material, which has higher mechanical strength and thermal stability than the organic polymer material in other preparation technologies.

[0039] Example 1

[0040] (1) Using ytterbium nitrate as solute and anhydrous ethanol as solvent, prepare an ytterbium nitrate solution 1 with a concentration of 1.5 mol / L.

[0041] (2) The metal mesh 2 is cleaned with anhydrous ethanol to remove organic attachments on its surface, then blown dry with compressed air and fixed on a fixture.

[0042] (3) Start the gas supply system 3 and adjust the gas supply volume so that the outer layer gas of the torch tube 5 is argon gas with a flow rate of 15 liters per minute, and the middle layer gas of the torch tube 5 is argon gas with a flow rate of 0.5 liters per minute; start the high-frequency generator 4, and adjust the plasma power to stabilize it at 1 kilowatt; the inductively coupled plasma device is moved by the mechanical arm, and the metal wire mesh 2 is preheated by scanning the flame flow 8 without injecting the solution. The moving path of the torch tube 5 relative to the metal wire mesh 2 is as follows: Figure 3 As shown, the moving speed is 200 mm / min and the track spacing is 3 mm.

[0043] (4) After the preheating of the metal mesh 2 is completed, an atomizing gas is input, and an atomized ytterbium nitrate solution 9 with a concentration of 2.5 mol / L is injected into the torch tube 5 through the peristaltic pump 4 and the atomizing nozzle 5, wherein the atomizing gas is argon gas with a flow rate of 0.5 liters per minute; the plasma power, the outer layer gas and the middle layer gas are consistent with those in step (3). It should be noted that the plasma power, the flow rate of the outer layer gas and the middle layer gas may also be inconsistent with those in step (3). After the plasma flame flow 8 is stabilized, the inductively coupled plasma device is moved by a robot arm to spray the metal mesh 2. The torch tube 5 is arranged in accordance with Figure 3 The "bow-shaped" path shown is moved to achieve full coverage spraying of the metal wire mesh 2, the moving speed is 200 mm per minute, the path spacing is 3 mm, and the number of spray layers is 20.

[0044] Figure 5The microstructure of the metal mesh after spraying in Example 1 at different magnifications is shown. It can be observed that the coating has completely covered the metal mesh, and a micron-sized cluster structure has been formed on the metal mesh, and nano-sized particles are distributed on the surface of the cluster structure. Figure 6 The water contact angle of the metal mesh after spraying in Example 1 is shown, and the contact angle is about 157°, showing super hydrophobic properties; Figure 7 The oil contact angle of the metal mesh after spraying in Example 1 (the oil here is n-hexane) is shown, and its contact angle is 0°, showing super oleophilic properties. The oil-water separation test is performed using a mixture of water and n-hexane. It can be observed that the oil in the mixture can quickly pass through the metal mesh, while the water is repelled by the metal mesh, which can achieve an efficient oil-water separation function.

[0045] Example 2

[0046] (1) Using ytterbium sulfate as the solute and distilled water as the solvent, prepare an ytterbium sulfate solution 1 with a concentration of 1 mol / L.

[0047] (2) The metal mesh 2 is cleaned with anhydrous ethanol to remove organic attachments on its surface, then blown dry with compressed air and fixed on a fixture.

[0048] (3) Start the gas supply system 3 and adjust the gas supply volume so that the outer layer gas of the torch tube 5 is argon gas with a flow rate of 15 liters per minute, and the middle layer gas of the torch tube 5 is argon gas with a flow rate of 0.5 liters per minute; start the high-frequency generator 4, and adjust the plasma power to stabilize it at 1 kilowatt; the inductively coupled plasma device is moved by the mechanical arm, and the metal wire mesh 2 is preheated by scanning the flame flow 8 without injecting the solution. The moving path of the torch tube 5 relative to the metal wire mesh 2 is as follows: Figure 3 As shown, the moving speed is 200 mm / min and the track spacing is 3 mm.

[0049] (4) After the preheating of the metal mesh 2 is completed, an atomizing gas is input, and an atomized ytterbium sulfate solution 9 with a concentration of 2.5 mol / L is injected into the torch tube 5 through the peristaltic pump 4 and the atomizing nozzle 5, wherein the atomizing gas is argon gas with a flow rate of 0.5 liters per minute; the plasma power, the outer layer gas and the middle layer gas are consistent with those in step (3). It should be noted that the plasma power, the flow rate of the outer layer gas and the middle layer gas may also be inconsistent with those in step (3). After the plasma flame flow 8 is stabilized, the inductively coupled plasma device is moved by a robot arm to spray the metal mesh 2. The torch tube 5 is arranged in accordance with Figure 3 The "bow-shaped" path shown is moved to achieve full coverage spraying of the metal wire mesh 2, the moving speed is 200 mm per minute, the path spacing is 3 mm, and the number of spray layers is 20.

[0050] Figure 8The microstructure of the metal mesh after spraying in Example 2 at different magnifications is shown. It can be observed that the coating has completely covered the metal mesh, and a micrometer-sized wrinkled structure is formed on the metal mesh, and nanometer-sized particles are distributed on the surface of the wrinkled structure; Fig. 9 The water contact angle of the metal mesh after spraying in Example 2 is shown, and the contact angle is about 150°, showing super hydrophobic properties; Fig.10 The oil contact angle of the metal mesh after spraying in Example 2 (the oil here is n-hexane) is shown, and its contact angle is about 3°, showing super oleophilic properties. Using a mixture of water and n-hexane for oil-water separation test, it can be observed that the oil in the mixture can quickly pass through the metal mesh, while the water is repelled by the metal mesh, which can achieve efficient oil-water separation function.

[0051] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An inductively coupled plasma spraying method for preparing an oil-water separation membrane, characterized in that: The following steps are involved: Step 1: Use anhydrous ethanol to clean the metal mesh to remove organic attachments on its surface, then use compressed air to blow it dry and fix it on the fixture; Step 2: Start the inductively coupled plasma generator and use the pure plasma flame to quickly scan the metal wire mesh for preheating without any raw material injection; Step 3: After the preheating is completed, a precursor solution of ytterbium oxide is injected into the plasma flame flow as a spraying raw material, and after the flame flow is stabilized, the surface of the metal wire mesh is sprayed to obtain a super-hydrophobic / super-oleophilic mesh film, wherein the super-hydrophobic / super-oleophilic mesh film is a rare earth oxide film; wherein the precursor solution of ytterbium oxide is an ytterbium nitrate solution or an ytterbium sulfate solution; The step 3 specifically comprises: after the preheating of the metal wire mesh is completed, inputting atomizing gas, and injecting the atomized solution into the innermost layer of the torch tube through a peristaltic pump and an atomizing nozzle, wherein the atomizing gas is argon gas with a flow rate of 0.5-1 liter per minute, the outer layer gas is argon gas with a flow rate of 10-20 liters per minute, and the middle layer gas is argon gas with a flow rate of 0.5-2 liters per minute; the concentration of the ytterbium oxide precursor solution is 1-2.5 mol per liter, and the ytterbium oxide precursor solution is 0.5-1.5 liters per minute. After the argon gas of 1000 g is atomized, it is injected into the innermost layer of the torch tube through a nozzle with an inner diameter of 0.5-2.5 mm, and the liquid delivery rate is 30-100 microliters per minute; the distance between the torch tube outlet and the metal wire mesh is 60-100 mm; after the plasma flame flow is stable, the inductively coupled plasma device is driven by a robotic arm to move and spray the metal wire mesh. The torch tube moves along a "bow-shaped" path, and the moving speed of the metal wire mesh relative to the torch tube is 200-500 mm per second, and the number of spray layers is 20-50.

2. The inductively coupled plasma spraying method for preparing an oil-water separation membrane according to claim 1, characterized in that: The ytterbium nitrate solution is a solution prepared with ytterbium nitrate as solute and anhydrous ethanol and / or distilled water as solvent; the ytterbium sulfate solution is a solution prepared with ytterbium sulfate as solute and anhydrous ethanol and / or distilled water as solvent.

3. The inductively coupled plasma spraying method for preparing an oil-water separation membrane according to claim 1, characterized in that: The metal wire mesh is made of stainless steel wire mesh, brass wire mesh or nickel-based alloy wire mesh.

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