Preparation and application of a filter-type superhydrophilic / underwater superoleophobic material for efficient emulsion separation

Abstract

The present invention discloses the preparation and application of a filtering super-hydrophilic / underwater super-oleophobic material for efficient emulsion separation. The material is based on a metal rubber obtained by stamping, which is immersed in a ferric chloride solution and added with a sodium borohydride solution to grow an iron oxide nano-sheet structure on its surface. The metal rubber is then immersed in a nano-silica dispersion prepared by a sol-gel method, and then combined to form a nano-silica particle micro-convex structure on its surface, which is then cured by heating, thereby significantly improving the overall surface roughness of the material and significantly improving the wear resistance, corrosion resistance and stability of the material, so that the resulting super-hydrophilic / underwater super-oleophobic material has efficient oil-water emulsion separation performance, long-lasting super-hydrophilic / underwater super-oleophobic stability and excellent mechanical stability and corrosion resistance.

Description

Technical Field

[0001] The present invention belongs to the field of superwetting materials, and in particular relates to the preparation and application of a filtering superhydrophilic / underwater superoleophobic material for efficient emulsion separation. Background Art

[0002] Common oily wastewater is primarily classified into three types: lamellar oil-water, dispersed oil, and oil-water emulsions (oil-in-water and oil-in-water emulsions). Oil-water emulsions have the smallest particle size (<20 μm), and the presence of surfactants makes the emulsified oil chemically more stable, posing a greater challenge for separation. Consequently, the development of oil-water separation technologies is particularly urgent. Current separation technologies often suffer from time-consuming and inefficient processes, necessitating innovative and efficient solutions. Within this context, the development of advanced emulsion separation materials is crucial. In particular, superhydrophilic / underwater superoleophobic materials with low surface energy and high surface roughness are crucial. However, the surface microstructure of these materials is extremely sensitive to mechanical wear and impact, making them susceptible to damage, limiting their stability and durability in practical applications. Therefore, improving the mechanical strength and environmental adaptability of superhydrophilic / underwater superoleophobic materials remains a key challenge in current research.

[0003] Metal rubber is a homogeneous, elastic, porous material. A wire winding machine winds a metal wire into a blank with a fixed pitch according to a certain pattern, and then cold-stamps it in a mold. Due to its excellent mechanical properties, such as vibration damping, sound insulation and noise reduction, and throttling sealing, it is widely used in aerospace, automotive, shipbuilding, land weapons, flame-retardant, and explosion-proof devices. The raw materials and processing technology used in the preparation of metal rubber give it a three-dimensional mesh structure. Its porosity and dirt-holding capacity can be changed by controlling different molding pressures and wire diameters. It also has the advantages of high load-bearing capacity and long service life. Compared with other filter materials, it can exert incomparable advantages in harsh environments such as aerospace, defense equipment, and special working conditions. Therefore, the development of wear-resistant, durable, and adsorbent oil-water emulsion separation composite materials based on metal rubber is of great value in protecting the environment and recycling oils. Summary of the Invention

[0004] In response to the above problems, the purpose of the present invention is to give metal rubber super-hydrophilic properties through a preparation process based on bionic super-hydrophilic materials, thereby preparing a filtering super-hydrophilic / underwater super-oleophobic material that is corrosion-resistant, durable and has good emulsion separation performance.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A filtering super-hydrophilic / underwater super-oleophobic material for efficient emulsion separation is based on a metal rubber substrate, on the surface of which self-grown iron oxide flake structures are attached with zero-dimensional spherical hydrophilic silica nanoparticles.

[0007] The preparation method of the filter-type super-hydrophilic / underwater super-oleophobic material comprises the following steps:

[0008] a) Winding the metal wire into a spiral coil through a wire winding machine;

[0009] b) placing the spiral roll in a metal mold, stamping it in stages to form a metal rubber, and then ultrasonically cleaning it and drying it for later use;

[0010] c) adding solid ferric chloride hexahydrate to deionized water and stirring to prepare a ferric chloride solution;

[0011] d) adding sodium borohydride to deionized water and stirring to prepare a sodium borohydride solution;

[0012] e) adding an ethanol solution of tetraethyl orthosilicate (TEOS) to an ethanol / water solution of ammonia, and adding polyvinylpyrrolidone (PVP) as a dispersant, and stirring to form a mixed solution;

[0013] f) placing the cleaned metal rubber in step b) into the ferric chloride solution prepared in step c) and stirring for a predetermined period of time, then dropwise adding the sodium borohydride solution prepared in step d) and continuing stirring for a predetermined period of time, then taking it out, vacuum drying it, and then placing it into the mixed solution prepared in step e) and soaking it for a predetermined period of time;

[0014] g) taking out the material prepared in step f), placing it in a vacuum muffle furnace for curing and drying, thereby obtaining the filter-type super-hydrophilic / underwater super-oleophobic material.

[0015] Furthermore, the material of the metal wire in step a) includes stainless steel, aluminum alloy, high carbon steel, copper alloy, titanium alloy, and its diameter is 0.12-0.3 mm.

[0016] Furthermore, the spiral coil obtained in step a) has a pitch of 0.8-2.2 mm and a porosity of 20-40%.

[0017] Furthermore, the shape of the metal mold in step b) includes cylinder, cuboid, cube, sphere, ellipsoid, prism, and three-dimensional ring.

[0018] Furthermore, the specific operation of the staged stamping in step b) is: stamping downwards to a predetermined height at a speed of 3 mm / min on a stamping machine and maintaining the speed for 1.5 minutes.

[0019] Furthermore, the diameter of the metal rubber obtained in step b) is 24 mm.

[0020] Furthermore, the ultrasonic cleaning time in step b) is 15 minutes.

[0021] Furthermore, the concentration of the ferric chloride solution obtained in step c) is 0.43 g / 20 mL.

[0022] Furthermore, the concentration of the sodium borohydride solution obtained in step d) is 0.03 g / 10 mL.

[0023] Furthermore, the mass ratio of tetraethyl orthosilicate, ammonia water, and polyvinyl pyrrolidone used in step e) is 2:100:1; and the volume ratio of ethanol to water in the ethanol / water solution of ammonia water is 4:3.

[0024] Furthermore, in step f), the metal rubber is placed in a ferric chloride solution and stirred for 15 minutes, and then the sodium borohydride solution is added dropwise and stirred for 45 minutes, and then immersed in the mixed solution for 30 minutes.

[0025] Furthermore, the curing and drying temperature in step g) is 120° C. and the time is 30 minutes.

[0026] The filter-type superhydrophilic / underwater superoleophobic material can be used for separation of oil-in-water emulsions.

[0027] Furthermore, the applicable oil phase is one or more of n-hexane, petroleum ether, 1,4-dimethylbenzene, 1,2-dichloroethane and toluene.

[0028] The preparation process of the material in the present invention does not require the use of any binding agent. It mainly utilizes the rough structure and hydrophilic high surface energy characteristics of the two-dimensional composite structure itself formed by the iron oxide flakes combined with nano-spherical silica particles. This can avoid the problem of material separation performance degradation caused by the swelling of the adhesive when separating the emulsion for a long time, and can avoid causing secondary damage to the environment. At the same time, the two-dimensional composite irregular structure formed by the iron oxide flakes combined with the nano-spherical silica particles in the material of the present invention forms a three-dimensional super-hydrophilic / underwater super-oleophobic layer with the metal rubber. In addition to intercepting the oil droplets in the oil-in-water emulsion, its internal cross-wound structure can also serve as a pipeline for oil transportation, accelerate the separation efficiency of the emulsion, and greatly enhance the stability and mechanical properties of the overall composite material.

[0029] The present invention has the following advantages:

[0030] (1) In order to address the shortcomings of superhydrophilic materials, such as poor mechanical properties and poor wear resistance, the present invention, during the preparation of metal rubber, winds the metal wire into a spiral coil and eliminates the residual preload of the material by means of staged stamping. The obtained metal rubber is then stirred in a ferric chloride solution and dripped with a sodium borohydride solution, and then immersed in a nano-silicon dioxide dispersion solution. Finally, after drying and curing in a vacuum muffle furnace, a filter-type superhydrophilic / underwater superoleophobic material with corrosion resistance, durability, and good emulsion separation performance is prepared. The formula of the present invention is scientific and reasonable, and the process flow is simple and practical. The obtained material can be used for the recovery of oil leaks at sea and the treatment of daily oily wastewater, and has extremely high environmental protection value and broad application space.

[0031] (2) The present invention uses metal rubber as a substrate to prepare a filter-type super-hydrophilic / underwater super-oleophobic material with excellent mechanical properties, corrosion resistance, durability, and good emulsion separation performance. Among them, the metal rubber has the characteristics of wear resistance, vibration resistance, high temperature resistance, etc., and has a uniform cross-porous structure, providing an excellent metal frame. The iron oxide sheet and the hydrophilic nano-silica spherical composite structure grow and adhere on the metal rubber wire to form a surface roughening modification, which greatly improves the emulsion separation ability of the metal rubber, so that it can separate a variety of water-in-oil emulsions, especially the difficult-to-separate water-in-oil emulsions formed by the mixture of emulsified lubricating oil and anti-wear oil produced in aviation machinery systems and water. At the same time, the super-wetting material is compounded on the metal rubber with a relatively high porosity structure, which improves the mechanical properties, durability and stability of the super-wetting material.

[0032] (3) The present invention in situ grows iron oxide flakes combined with nano-spherical silica particles on the metal rubber wire to form a two-dimensional composite structure, which gives the material excellent high surface energy and hydrophilic and oleophobic wettability. In addition, because the filter material is a three-dimensional material with multi-pore and multi-connectivity characteristics, it can also separate oil-in-water emulsions with relatively complex components and high viscosity, such as cutting oils and anti-wear oils used in mechanical processing, as well as cosmetic oils and food oils used in daily life. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Actual images and SEM micrographs of the metal rubber MR (a, e) obtained by stamping and the filtering superhydrophilic / underwater superoleophobic material P-MRFS (bd, fg) prepared in the example.

[0034] Figure 2 This is the EDS spectrum of the filtering super-hydrophilic / underwater super-oleophobic material P-MRFS prepared in the example.

[0035] Figure 3SEM images and XPS spectra of the metal rubber MR (a) obtained by stamping and the filtering superhydrophilic / underwater superoleophobic material P-MRFS (b) prepared in the embodiment.

[0036] Figure 4 Figure 1 shows the corrosion resistance of the filter-type metal rubber super-hydrophilic / underwater super-oleophobic material P-MRFS prepared in the examples. Figure a shows the Tafel plots of the metal rubber MR and P-MRFS in acid-base and salt environments, respectively; b shows the underwater oil contact angles of the P-MRFS after 48 hours in deionized water and in an acid-base and salt environment, respectively; c shows the contact angle curves of the P-MRFS in deionized water and in an acid-base and salt environment over 48 hours; and d shows the oil-water separation efficiency of the P-MRFS after 1, 3, and 7 days in the acid-base and salt environment.

[0037] Figure 5 Figure 1 shows the wear resistance of the filter-type superhydrophilic / underwater superoleophobic material P-MRFS prepared in this example. Figure a shows a schematic diagram of the friction performance experiment, b shows the underwater oil contact angle of P-MRFS after friction distances of 0 cm, 200 cm, and 400 cm, c shows the underwater oil contact angle and underwater oil rolling angle of P-MRFS within a friction distance of 400 cm, and d shows the flux of P-MRFS for various oil-in-water emulsions after a friction distance of 400 cm and the purity of the separated water.

[0038] Figure 6 Figure 1 shows the emulsion separation performance of the filter-type superhydrophilic / underwater superoleophobic material P-MRFS prepared in the examples. Figure a shows the oil-water separation device, b shows optical micrographs of the oil-in-water emulsion and filtrate before and after separation of five oil-in-water emulsions, c shows the particle size distribution of the five oil-in-water emulsions before separation, d shows the particle size distribution of the five oil-in-water emulsions after separation, e shows the underwater oil contact angle values ​​for the five oil-in-water emulsions, f shows the separation flux and separation efficiency for the five oil-in-water emulsions, and g shows the flux and efficiency changes of the emulsion separation cycle using n-hexane.

[0039] Figure 7 These are the emulsion separation performance diagrams of the materials P-MRF (a) and P-MRS (b) prepared in Comparative Examples 1 and 2. DETAILED DESCRIPTION

[0040] A filter-type super-hydrophilic / underwater super-oleophobic material for efficient emulsion separation, the preparation of which comprises the following steps:

[0041] a) Winding the metal wire into a spiral coil through a wire winding machine;

[0042] b) The spiral coil is placed in a metal mold and stamped into a metal rubber with a diameter of 24 mm by staged pressing. The metal rubber is ultrasonically cleaned with ethanol and deionized water for 15 minutes each and then dried for later use;

[0043] c) adding solid ferric chloride hexahydrate to deionized water and stirring to prepare a 0.43 g / 20 mL ferric chloride solution;

[0044] d) adding sodium borohydride to deionized water and stirring to prepare a 0.03 g / 10 mL sodium borohydride solution;

[0045] e) adding an ethanol solution of tetraethyl orthosilicate (TEOS) to an ethanol / water solution of ammonia (4:3, v / v), adding polyvinylpyrrolidone (PVP) as a dispersant, and stirring to form a mixed solution;

[0046] f) placing the cleaned metal rubber in step b) into the ferric chloride solution prepared in step c) and stirring for 15 minutes, then dropwise adding the sodium borohydride solution prepared in step d) and continuing stirring for 45 minutes. Afterwards, the metal rubber was removed, vacuum dried, and then immersed in the mixed solution prepared in step e) for 30 minutes.

[0047] g) The material prepared in step f) was taken out, placed in a vacuum muffle furnace, and cured and dried at 120° C. for 30 min to obtain a filterable super-hydrophilic / underwater super-oleophobic material.

[0048] The metal wire in step a) is made of stainless steel, aluminum alloy, high carbon steel, copper alloy, or titanium alloy, and has a diameter of 0.12-0.3 mm. The resulting spiral coil has a pitch of 0.8-2.2 mm and a porosity of 20-40%.

[0049] The shape of the metal mold in step b) includes a cylinder, a cuboid, a cube, a sphere, an ellipsoid, a prism, and a three-dimensional ring. The specific operation of the staged stamping is: stamping downward on the stamping machine at a speed of 3 mm / min to a predetermined height and holding it for 1.5 minutes.

[0050] The mass ratio of tetraethyl orthosilicate, ammonia water and polyvinyl pyrrolidone used in step e) is 2:100:1.

[0051] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention. Example

[0052] (1) A metal wire with a diameter of 0.1 m is wound into a spiral coil with a pitch of 1.5 mm and a porosity of 20-40% by a wire winding machine;

[0053] (2) 5 g of spiral coil was placed in a cylindrical metal mold and stamped into a cylindrical metal rubber with a diameter of 24 mm by staged stamping. After ultrasonic cleaning with ethanol and deionized water for 15 min each, it was dried for later use;

[0054] (3) Add 0.43 g of solid ferric chloride hexahydrate to 20 ml of deionized water and stir to prepare a ferric chloride solution;

[0055] (4) Add 0.15 g of sodium borohydride to 50 ml of deionized water and stir to prepare a sodium borohydride solution;

[0056] (5) Using the sol-gel method, 11.43 mL of a 25 vol% ethanol solution of tetraethyl orthosilicate (TEOS) was added to 6.42 mL of an ethanol / water solution (4:3, v / v) containing 2.15 mL of ammonia water, and stirred to prepare a mixed solution. During the stirring process, 0.2% polyvinyl pyrrolidone (K30) was added as a dispersant.

[0057] (6) Place the prepared metal rubber in a ferric chloride solution and stir for 15 minutes, then drop the sodium borohydride solution into it, continue stirring for 45 minutes, take it out, vacuum dry it for 30 minutes, and then place it in the mixed solution prepared in step (5) and soak it for 30 minutes;

[0058] (7) The material prepared in step (6) was taken out and placed in a vacuum muffle furnace at 120°C for vacuum drying for 30 min to obtain a filter-type superhydrophilic / underwater superoleophobic material, which was labeled as P-MRFS.

[0059] Comparative Example 1

[0060] (1) A metal wire with a diameter of 0.1 mm is wound into a spiral coil with a pitch of 1.5 mm and a porosity of 20-40% using a wire winding machine;

[0061] (2) 5 g of spiral coil was placed in a cylindrical metal mold and stamped into a cylindrical metal rubber with a diameter of 24 mm by staged stamping. After ultrasonic cleaning with ethanol and deionized water for 15 min each, it was dried for later use;

[0062] (3) Add 0.43 g of solid ferric chloride hexahydrate to 20 ml of deionized water and stir to prepare a ferric chloride solution;

[0063] (4) Add 0.15 g of sodium borohydride to 50 ml of deionized water and stir to prepare a sodium borohydride solution;

[0064] (5) Place the prepared metal rubber in ferric chloride solution and stir for 15 minutes, then drop sodium borohydride solution into it, continue stirring for 45 minutes, then take it out and vacuum dry it for 30 minutes;

[0065] (6) The material prepared in step (5) was taken out and placed in a vacuum muffle furnace at 120°C for vacuum drying for 30 min. The obtained material was marked as P-MRF.

[0066] Comparative Example 2

[0067] (1) A metal wire with a diameter of 0.1 mm is wound into a spiral coil with a pitch of 1.5 mm and a porosity of 20-40% using a wire winding machine;

[0068] (2) 5 g of spiral coil was placed in a cylindrical metal mold and stamped into a cylindrical metal rubber with a diameter of 24 mm by staged stamping. After ultrasonic cleaning with ethanol and deionized water for 15 min each, it was dried for later use;

[0069] (3) Using the sol-gel method, 11.43 mL of a 25 vol% ethanol solution of tetraethyl orthosilicate (TEOS) was added to 6.42 mL of an ethanol / water solution (4:3, v / v) containing 2.15 mL of ammonia water, and stirred to form a mixed solution. During the stirring process, 0.2% polyvinyl pyrrolidone (K30) was added as a dispersant.

[0070] (4) Soak the prepared metal rubber in a 4 mg / mL dopamine solution for 24 hours, and then soak it in the mixed solution prepared in step (3) for 30 minutes;

[0071] (5) The material prepared in step (4) was taken out and placed in a vacuum muffle furnace at 120°C for vacuum drying for 30 min. The obtained material was labeled P-MRS.

[0072] Figure 1 The following are physical images and SEM micrographs of the metal rubber MR obtained by stamping and the filtering super-hydrophilic / underwater super-oleophobic material P-MRFS prepared in this embodiment. As can be seen from the figure, the surface of the original metal rubber is smooth without any rough structure (e), while in the P-MRFS, iron oxide sheets are combined with nano-spherical silica particles to form a two-dimensional composite irregular structure and are evenly distributed on the surface of the metal rubber material (d, h). Moreover, by comparing the illustrations in e, f, and h, it can be seen that, from the wettability level, compared with the super-hydrophilic / oleophilic properties of MR in air (both reaching 0°), P-MRFS has excellent underwater super-oleophobic properties (UWOCA reaches 0° and 156°).

[0073] Figure 2 This is the EDS spectrum of the filter-type super-hydrophilic / underwater super-oleophobic material P-MRFS prepared in this example. EDS results show that the material surface contains Fe, Si, C, O, and N elements.

[0074] Figure 3The SEM images and XPS spectra of the metal rubber MR (a) obtained by stamping and the filtering super-hydrophilic / underwater super-oleophobic material P-MRFS (b) prepared in this example. The figure shows the coexistence of elements Fe, Si, O, C and N in P-MRFS. Among them, the increase in the main peaks of Fe, Si, N and O elements indicates the successful attachment of iron oxide sheets and the successful attachment of silica nanoparticles. At the same time, the appearance of Fe2P1 in the figure indicates the presence and generation of iron oxide and ferrous oxide, which further proves that the composition of the nanosheet structure is mainly a composite of iron oxide and ferrous oxide.

[0075] Corrosion resistance experiments were conducted using metal rubber MR and filter-type super-hydrophilic / underwater super-oleophobic material P-MRFS. The specific operation was to immerse the metal rubber MR and P-MRFS in acid, alkali and salt corrosive solutions, measure their corrosion potential (Ecorr) and corrosion current density (Icorr) of the samples in 3.5wt% NaCl solution, NaOH (pH=13) solution and HCl (pH=2) solution, and measure their corresponding potentiodynamic polarization curves. The Tafel extrapolation method was used to analyze the corrosion potential (Ecorr) and corrosion current density (Icorr) of the samples using an electrochemical workstation. The results are shown in Figure 4 And Table 1.

[0076] Table 1 Corrosion resistance characterization data of MR and P-MRFS

[0077]

[0078] Generally, high corrosion potential and low corrosion current density mean that the material has good corrosion resistance. The results in Table 1 show that under three different corrosion environments, the corrosion potential of P-MRFS is greater than that of metal rubber MR, and the corrosion current density of P-MRFS is smaller. Therefore, it is proved that P-MRFS has higher corrosion resistance. Combined with the analysis of electron microscopy results, it can be seen that the surface of P-MRFS is covered with a uniform flaky metal iron oxide structure and a large amount of spherical silica material is attached to the surface of the flaky structure. Since silica itself has strong corrosion resistance and stability, it will accommodate more air and form an air film between the corrosive liquid and the material, thereby reducing the corrosion area and improving the corrosion resistance. At the same time, the three-dimensional framework based on metal rubber can avoid direct contact between the interior of the material and the corrosive liquid, indirectly improving the corrosion resistance of the material.

[0079] At the same time, by Figure 4The results show that after 48 hours of immersion in a corrosive environment, the underwater oil contact angle of P-MRFS shows a slight decrease, but maintains a high oleophobicity of 149° (b, c). Based on wettability and oil-water separation theory, such a high underwater oleophobic angle fully guarantees high separation performance. Furthermore, the oil-in-water separation efficiency of P-MRFS remains above 99.5% after 1, 3, and 7 days in acid, alkali, and salt solutions (d). This demonstrates that P-MRFS possesses excellent corrosion-resistant oil-water separation capabilities.

[0080] The wear resistance test was carried out using the filter-type super-hydrophilic / underwater super-oleophobic material P-MRFS. Specifically, the filter-type super-hydrophilic / underwater super-oleophobic material was subjected to a friction cycle test under a 200g weight. The results are shown in Figure 5 .Depend on Figure 5 It can be seen that with the increase in the number of friction cycles, the underwater oil contact angle (UWOCA) gradually increases and eventually stabilizes at around 158°, and the underwater oil rolling angle gradually increases and eventually stabilizes at a stable value of approximately 15° (c). Furthermore, electron microscopy images before and after wear show that during the wear process, the metal rubber provides a solid framework for the spherical structure. Furthermore, the P-MRFS flux and water purity remain largely unchanged after wear, indicating that the P-MRFS can maintain high separation efficiency even after surface wear (d). This demonstrates that the P-MRFS has good mechanical durability. Furthermore, the three-dimensional framework based on the metal rubber can prevent direct friction and wear within the material, thereby ensuring the integrity of the internal silk composite structure and its separation capability, indirectly improving the material's durability.

[0081] The filter-type super-hydrophilic / underwater super-oleophobic material P-MRFS prepared in the example was used to conduct an emulsion separation experiment. The emulsion used was an oil-in-water emulsion of n-hexane, petroleum ether, 1,4-dimethylbenzene, 1,2-dichloroethane and toluene, with a water-to-oil volume ratio of 100:1, and Tween 80 was added as a surfactant stabilizer. The results are shown in Figure 6 .

[0082] Depend on Figure 6 It can be seen that micron-sized water droplets were observed in the lubricating oil, but no water droplets were observed in the filtrate (b). At the same time, the particle size distribution diagrams in the emulsion before separation and the filtrate after separation show that the number of emulsion droplets in the filtrate is significantly reduced compared with the former, indicating that the surfactant-stabilized water-in-oil emulsion has been eliminated (c, d). The underwater oil contact angles of the five water-in-oil emulsions all reach above 150° (e), meeting the prerequisite for emulsion separation; and the separation efficiency and flow rate data show that its efficiency can reach above 99.5% and maintain a large flow rate (f, g), which proves that the filtration-type superhydrophilic / underwater superoleophobic material can efficiently separate water-in-oil emulsions.

[0083] Under the same experimental conditions, the oil-water separation experiments were carried out on five kinds of oil-in-water emulsions using P-MRF and P-MRS prepared in the comparative example. The results are shown in Figure 7 .Depend on Figure 7 It can be seen that the average separation efficiency of both for the five oil-in-water emulsions is below 90%, which cannot meet the requirements of high-efficiency separation. It can be seen that compared with a single attached material, the separation efficiency and separation flux of P-MRFS are significantly improved.

[0084] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing a filter-type super-hydrophilic / underwater super-oleophobic material, wherein the material is composed of a metal rubber substrate, a self-grown iron oxide flake structure on the surface, and zero-dimensional spherical hydrophilic silica nanoparticles attached thereto, characterized in that: The steps include: a) Winding the wire into a spiral coil; b) placing the spiral roll in a metal mold, stamping it in stages to form a metal rubber, and then ultrasonically cleaning it and drying it for later use; c) adding solid ferric chloride hexahydrate to deionized water and stirring to prepare a ferric chloride solution; d) adding sodium borohydride to deionized water and stirring to prepare a sodium borohydride solution; e) adding the ethanol solution of tetraethyl orthosilicate to the ethanol / water solution of ammonia, adding polyvinyl pyrrolidone as a dispersant, and stirring to form a mixed solution; f) placing the cleaned metal rubber in step b) into the ferric chloride solution prepared in step c) and stirring for a predetermined period of time, then dropwise adding the sodium borohydride solution prepared in step d) and continuing stirring for a predetermined period of time, then taking it out, vacuum drying it, and then placing it into the mixed solution prepared in step e) and soaking it for a predetermined period of time; g) taking out the material prepared in step f), placing it in a vacuum muffle furnace for curing and drying, thereby obtaining the filter-type super-hydrophilic / underwater super-oleophobic material.

2. The preparation method of the filter type super hydrophilic / underwater super oleophobic material according to claim 1, wherein The metal wire in step a) is made of stainless steel, aluminum alloy, high carbon steel, copper alloy, and titanium alloy, and has a diameter of 0.12-0.3 mm. The pitch of the resulting spiral coil is 0.8-2.2 mm, and the porosity is between 20-40%.

3. The preparation method of the filter type super hydrophilic / underwater super oleophobic material according to claim 1, wherein The shapes of the metal mold in step b) include cylinder, cuboid, cube, sphere, ellipsoid, prism, and three-dimensional ring. The specific operation of the staged stamping is: stamping downward on the punching machine at a speed of 3 mm / min to a predetermined height and holding it for 1.5 minutes; the diameter of the resulting metal rubber is 24 mm.

4. The method for preparing a filter-type super-hydrophilic / underwater super-oleophobic material according to claim 1, wherein The concentration of the ferric chloride solution obtained in step c) is 0.43 g / 20 mL.

5. The preparation method of the filter type super hydrophilic / underwater super oleophobic material according to claim 1, characterized in that, The concentration of the sodium borohydride solution obtained in step d) is 0.03 g / 10 mL.

6. The method for preparing a filter-type super-hydrophilic / underwater super-oleophobic material according to claim 1, wherein: The mass ratio of tetraethyl orthosilicate, ammonia water and polyvinyl pyrrolidone used in step e) is 2:100:1; the volume ratio of ethanol to water in the ethanol / water solution of ammonia water is 4:

3.

7. The method for preparing a filter-type super-hydrophilic / underwater super-oleophobic material according to claim 1, wherein: In step f), the metal rubber is placed in a ferric chloride solution and stirred for 15 minutes, and then the sodium borohydride solution is added dropwise and stirred for 45 minutes, and then immersed in the mixed solution for 30 minutes.

8. The method for preparing a filter-type super-hydrophilic / underwater super-oleophobic material according to claim 1, wherein: The curing and drying temperature in step g) is 120° C. and the time is 30 minutes.

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