Super-hydrophilic oil-water separation membrane, and preparation method and application thereof

Abstract

The application provides an ultra-hydrophilic oil-water separation membrane and a preparation method and application thereof, and the preparation method comprises the following steps: (1) performing first calcination treatment on a metal mesh membrane to obtain a membrane base; (2) spin coating TiO2 sol on the membrane base, and then performing second drying treatment and second calcination treatment to obtain a TiO2-metal mesh composite membrane; and (3) immersing the TiO2-metal mesh composite membrane in an alkali solution to perform hydrothermal modification treatment, and obtaining the ultra-hydrophilic oil-water separation membrane after cleaning treatment. The oil-water separation membrane provided by the application has the performance of being ultra-hydrophilic and ultra-oleophobic, can handle emulsified oil which is difficult to separate, and has good chemical stability and mechanical stability, and can be operated stably for a long time under different environmental conditions. In addition, the preparation method combines physical and chemical methods, is simple to operate, does not need to add additional chemical reagents, is environmentally friendly, and has low energy consumption.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of separation membranes, and relates to an ultrahydrophilic oil-water separation membrane and a preparation method and application thereof, in particular to an ultrahydrophilic oil-water separation membrane for separating emulsified oil and a preparation method and application thereof. BACKGROUND

[0002] Oil-containing wastewater is one of the environmental pollutions that researchers are currently troubled by in the society, and improper treatment can cause water body deterioration, fish resource reduction, toxin enrichment and resource waste, and other problems. Effective separation and treatment of oil-water emulsion has become an indispensable part in industrial production, energy exploitation and urban management. Traditional oil-water separation methods include chemical method, biological method, physical-chemical method and biochemical method. However, these methods have problems such as low efficiency, high cost, complex process and secondary pollution, and cannot cope with the increasing discharge of oil-containing wastewater.

[0003] Oil-water separation membranes are usually composed of a supporting substrate and a special wettable surface coating, and are a kind of separation membranes that realize specific passage of oil phase or water phase by using special surface wettability. The ultrahydrophilic oil-water separation membrane has specific passage of water phase, and shows advantages such as high flux and easy cleaning in practical application.

[0004] CN 116764458A discloses an oil-water separation membrane and a preparation method and application thereof. The oil-water separation membrane is prepared by alkali treatment and hydrophilic modification of a polyvinylidene fluoride porous membrane. The modifier used in the hydrophilic modification is tannic acid and copper ions. The oil-water separation membrane provided by the patent uses a polyvinylidene fluoride porous membrane as a base film, first performs hydroxylation treatment on the base film by using an alkali reagent, and then constructs a Cu 2+ / TA coordination coating layer with good hydrophilicity on the surface of the membrane material by using copper ions and tannic acid. The oil-water separation membrane provided by the patent has good hydrophilicity and specific hierarchical roughness, has hydrophilicity / underwater superoleophobicity, and has good application prospect in the field of oil-containing wastewater treatment. The alkali treatment and hydrophilic modification steps involved in the preparation process of the patent are relatively complex, which increases the difficulty and cost of industrial application.

[0005] CN 116617881A discloses a kind of bionic superhydrophilic / underwater oleophobic MOF coating net film and its application, the preparation method of the coating net film is: first, stainless steel net film is washed and phosphorized, then a layer of MOF material is deposited on the net film by electrodeposition method, after calcination, polyvinylpyrrolidone is used to modify the MOF coating net film, i.e. bionic superhydrophilic / underwater oleophobic MOF coating net film is obtained.The MOF coating net film obtained by the patent shows good spreading and rapid permeability to water, the contact angle with water is 0 °, the water passing rate is 2 drops / s, and excellent superhydrophilic performance is shown.But the preparation process of the invention is complex, the uniformity of electrodeposited MOF material, the precise control of calcination conditions, so as to affect the water flux. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a superhydrophilic oil-water separation membrane and its preparation method and application, which has superhydrophilic and superoleophobic properties, can handle difficult to separate emulsified oil; and the oil-water separation membrane has good chemical stability and mechanical stability, and can be operated stably for a long time under different environmental conditions.In addition, the preparation method combines physical and chemical methods, which is simple to operate, does not require additional chemical reagents, is environmentally friendly and has low energy consumption.

[0007] To achieve the purpose of the present application, the following technical solutions are adopted:

[0008] In a first aspect, the present application provides a preparation method of a superhydrophilic oil-water separation membrane, comprising the following steps:

[0009] (1) first calcination treatment is carried out on the metal net film to obtain a membrane base;

[0010] (2) TiO2 sol is spin-coated on the membrane base obtained in step (1), and then second drying treatment and second calcination treatment are carried out to obtain a TiO2-metal mesh composite membrane;

[0011] (3) the TiO2-metal mesh composite membrane obtained in step (2) is immersed in an alkaline solution for hydrothermal modification treatment, and after cleaning treatment, the superhydrophilic oil-water separation membrane is obtained.

[0012] In the present application, by loading TiO2 on the metal net film, the TiO2-metal mesh composite membrane has superhydrophilic and superoleophobic properties, and can realize the separation of dispersed oil in oil-water mixture; then by using alkaline solution for hydrothermal modification, the obtained superhydrophilic oil-water separation membrane has the separation ability of emulsified oil in oil-water mixture;

[0013] The super-hydrophilic oil-water separation membrane prepared by the preparation method has excellent mechanical stability and chemical stability, can be stably operated for a long time under different environmental conditions, and realizes efficient separation of emulsified oil; and the preparation method combines physical and chemical methods, is simple to operate, does not need to add additional chemical reagents, is environmentally friendly, and has low energy consumption.

[0014] As a preferred technical solution of the present application, the metal mesh film in step (1) includes any one of a stainless steel mesh film, a copper mesh film or a titanium mesh film, and preferably a stainless steel mesh film.

[0015] In the present application, the metal mesh film in step (1) is preferably a stainless steel mesh film, because the stainless steel mesh film can form aluminum oxide on the surface of the mesh film during calcination, which can further improve the roughness of the mesh film surface and thus improve the bonding force between the film base and the TiO2 sol.

[0016] Preferably, the pore size of the metal mesh film in step (1) is 200-600 mesh, for example, it can be 200 mesh, 300 mesh, 400 mesh, 500 mesh or 600 mesh, but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0017] In the present application, the pore size of the metal mesh film is 200-600 mesh. When the mesh number increases, it represents that the pore size of the mesh gradually decreases, the flux decreases with the decrease of the mesh pore size, and the separation efficiency increases with the increase of the mesh pore size. When the mesh number is 200-600, a relatively balanced relationship between separation efficiency and flux can be achieved. If the pore size is too large, the flux of the obtained separation membrane will be too small, and the oil-water separation efficiency will be better; if the pore size is too small, the flux of the obtained separation membrane will be too large, and the oil-water separation efficiency will be reduced.

[0018] Preferably, the temperature of the first calcination treatment in step (1) is 700-800℃, for example, it can be 700℃, 720℃, 740℃, 760℃, 780℃ or 800℃, but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0019] Preferably, the time of the first calcination treatment in step (1) is 4-8h, for example, it can be 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h or 8h, but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0020] As a preferred technical solution of the present application, the first calcination treatment in step (1) further includes sequentially performed cleaning treatment and first drying treatment.

[0021] Preferably, the cleaning treatment in step (1) comprises: sequentially using 3% dilute hydrochloric acid, ethanol and deionized water for ultrasonic washing for 10 min.

[0022] Preferably, the temperature of the first drying treatment in step (1) is 50-70℃, for example, it can be 50℃, 54℃, 58℃, 62℃, 66℃ or 70℃, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0023] In the present application, the end point of the first drying treatment is to provide a water-free environment for the metal mesh film, and to provide a basis for subsequent calcination of the metal mesh film. The first calcination treatment in step (1) makes the mesh film have a rough structure, which is beneficial to the loading of TiO2sol, and improves the separation efficiency; when the temperature of the first calcination treatment is increased or decreased, it will be difficult to form a rough morphology on the surface, and thus the separation efficiency will be reduced.

[0024] As a preferred technical solution of the present application, the spin coating time in step (2) is 1-3 min, for example, it can be 1 min, 1.4 min, 1.8 min, 2.2 min, 2.6 min or 3 min, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0025] Preferably, the rotation speed of the spin coating in step (2) is 450-550 r / min, for example, it can be 450 r / min, 470 r / min, 490 r / min, 510 r / min, 530 r / min or 550 r / min, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0026] Preferably, the concentration of the TiO2sol in step (2) is 6-18 wt%, for example, it can be 6 wt%, 9 wt%, 12 wt%, 15 wt% or 18 wt%, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0027] In the present application, the thickness of the TiO2coating on the base film is adjusted by adjusting the concentration of the TiO2sol and the spin coating time. When the thickness of the TiO2coating increases, the rough morphology of the surface will be covered by the TiO2with a larger thickness, thereby reducing the separation efficiency.

[0028] In the present application, the preparation method of the TiO2sol in step (2) comprises: mixing deionized water, HCl and polyethylene glycol 400 in a tetrabutyl titanate (TBOT) ethanol (EtOH) solution, and then sequentially performing vigorous stirring and aging treatment for 24 h to obtain the TiO2sol.

[0029] Preferably, when the concentration of the TiO2 sol is 6wt%, the molar ratio of tetrabutyl titanate, ethanol, deionized water, HCl and polyethylene glycol 400 in the TiO2 sol is 1:12.2:2.5:0.08:0.1.

[0030] As a preferred technical solution of the present application, the temperature of the second drying treatment in step (2) is 60-130℃, for example, it can be 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃ or 130℃, but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0031] Preferably, the time of the second drying treatment in step (2) is 6-18h, for example, it can be 6h, 8h, 10h, 12h, 14h, 16h or 18h, but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0032] As a preferred technical solution of the present application, the temperature of the second calcination treatment in step (2) is 350-450℃, for example, it can be 350℃, 370℃, 390℃, 410℃, 430℃ or 450℃, but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0033] Preferably, the time of the second calcination treatment in step (2) is 2-6h, for example, it can be 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h, but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0034] In the present application, the purpose of the second drying treatment is to remove physically combined water and organic components in the TiO2 sol; the purpose of the second calcination treatment is to make the TiO2 sol lose chemically combined water and turn into TiO2 crystals with good crystallinity; when the temperature or time of the second calcination treatment is too high (excessive calcination), the obtained TiO2-metal mesh composite membrane will crack due to high temperature, thereby affecting the binding force of the membrane and the oil-water separation effect.

[0035] As a preferred technical solution of the present application, the alkali solution in step (3) includes sodium hydroxide solution and / or potassium hydroxide solution.

[0036] Preferably, the concentration of the alkali solution in step (3) is 8-12mol / L, for example, it can be 8mol / L, 9mol / L, 10mol / L, 11mol / L or 12mol / L, but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0037] As a preferred technical solution of the present application, the temperature of the hydrothermal modification treatment in step (3) is 100-200℃, for example, it can be 100℃, 120℃, 140℃, 160℃, 180℃ or 200℃, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0038] Preferably, the time of the hydrothermal modification treatment in step (3) is 8-16h, for example, it can be 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h or 16h, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0039] In the present application, the hydrothermal modification treatment in step (3) can make the TiO2-metal mesh composite film have good demulsification capacity, further improving the separation effect of oil-water mixture.

[0040] In addition, when the time of the hydrothermal modification treatment is too long, the TiO2 sheet stack structure will be too dense, which will weaken the bonding force and reduce the oil-water separation flux; if the treatment time is too short, the TiO2 sheet stack structure will be too loose, which is not conducive to improving the oil-water separation efficiency.

[0041] As a preferred technical solution of the present application, the preparation method of the super-hydrophilic oil-water separation film provided in the first aspect of the present application comprises the following steps:

[0042] (1) sequentially performing cleaning treatment, first drying treatment and first calcination treatment on a metal mesh film to obtain a film base;

[0043] The pore size of the metal mesh film is 200-600 mesh; the temperature of the first calcination treatment is 700-800℃, and the time is 4-8h;

[0044] (2) spin coating TiO2 sol on the film base obtained in step (1), and then performing second drying treatment and second calcination treatment to obtain a TiO2-metal mesh composite film;

[0045] The spin coating time is 1-3min, and the rotation speed is 450-550r / min; the concentration of the TiO2 sol is 6-18wt%;

[0046] The temperature of the second drying treatment is 60-130℃, and the time is 6-18h; the temperature of the second calcination treatment is 350-450℃, and the time is 2-6h;

[0047] (3) immersing the TiO2-metal mesh composite film obtained in step (2) in an alkali solution with a concentration of 8-12mol / L for hydrothermal modification treatment, and obtaining the super-hydrophilic oil-water separation film after cleaning treatment;

[0048] The temperature of the hydrothermal modification treatment is 100-200 DEG C, and the time is 8-16 hours.

[0049] In a second aspect, the present application provides an ultra-hydrophilic oil-water separation membrane, which is prepared by the method provided in the first aspect.

[0050] It is worth mentioning that the ultra-hydrophilic oil-water separation membrane provided by the present application has a pipeline array structure, and the thickness is 3-5 μm, for example, it can be 3 μm, 3.4 μm, 3.8 μm, 4.2 μm, 4.6 μm or 5 μm, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0051] In a third aspect, the present application provides an application of the ultra-hydrophilic oil-water separation membrane prepared by the method provided in the first aspect, and the ultra-hydrophilic oil-water separation membrane is used for separating an oil-water mixture.

[0052] The particle size of the oil in the oil-water mixture is 0.1-100 μm, for example, it can be 0.1 μm, 10 μm, 30 μm, 50 μm, 70 μm or 100 μm, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0053] The numerical range of the present application includes not only the above-mentioned point values, but also any point values between the above-mentioned numerical ranges which are not mentioned, and the present application does not list the specific point values included in the range for the sake of brevity and simplicity.

[0054] Compared with the prior art, the present application has the following beneficial effects:

[0055] (1) The ultra-hydrophilic oil-water separation membrane provided by the present application has the properties of super-hydrophilic and super-oleophobic and good demulsification function, and can effectively separate the emulsified oil in the oil-water mixture;

[0056] (2) The ultra-hydrophilic oil-water separation membrane provided by the present application has good chemical stability and mechanical stability, and can be stably operated for a long time under different environmental conditions;

[0057] (3) The preparation method provided by the present application combines physical and chemical methods, is simple to operate, does not need to add additional chemical reagents, is environmentally friendly, and has low energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 The scanning electron microscope image of the ultra-hydrophilic oil-water separation membrane provided for Example 1 of the present application;

[0059] Figure 2 The content diagram of the emulsified oil in the emulsion oil-water when different separation membranes are used for separation. DETAILED DESCRIPTION

[0060] The technical solutions of the present application are further illustrated by the specific embodiments below. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0061] Embodiment 1

[0062] The present embodiment provides a super-hydrophilic oil-water separation membrane, and a preparation method of the super-hydrophilic oil-water separation membrane comprises the following steps:

[0063] (1) sequentially performing cleaning treatment, first drying treatment and first calcination treatment on a stainless steel mesh membrane to obtain a membrane base;

[0064] The pore size of the stainless steel mesh membrane is 600 meshes; the temperature of the first calcination treatment is 800℃, and the time is 6h;

[0065] (2) spin coating TiO2sol on the membrane base obtained in step (1), and then performing second drying treatment and second calcination treatment to obtain a TiO2-metal mesh composite membrane;

[0066] The spin coating time is 1min, and the rotation speed is 500r / min; the concentration of the TiO2sol is 6wt%;

[0067] The temperature of the second drying treatment is 120℃, and the time is 12h; the temperature of the second calcination treatment is 400℃, and the time is 2h;

[0068] (3) immersing the TiO2-metal mesh composite membrane obtained in step (2) in a sodium hydroxide solution with a concentration of 10mol / L to perform hydrothermal modification treatment, and obtaining the super-hydrophilic oil-water separation membrane after cleaning treatment;

[0069] The temperature of the hydrothermal modification treatment is 150℃, and the time is 12h.

[0070] The scanning electron microscope image of the super-hydrophilic oil-water separation membrane provided by the present embodiment is shown in Figure 1 According to Figure 1 It can be known that the super-hydrophilic oil-water separation membrane provided by the present application has a neat pipeline array structure.

[0071] Embodiment 2

[0072] The present embodiment provides a super-hydrophilic oil-water separation membrane, and a preparation method of the super-hydrophilic oil-water separation membrane comprises the following steps:

[0073] (1) sequentially performing cleaning treatment, first drying treatment and first calcination treatment on a stainless steel mesh membrane to obtain a membrane base;

[0074] The pore size of the titanium mesh film is 200 meshes; the first calcination treatment is performed at a temperature of 700 DEG C for 8 hours;

[0075] (2) The TiO2sol is spin-coated on the film substrate obtained in step (1), and then a second drying treatment and a second calcination treatment are performed to obtain a TiO2-metal mesh composite film;

[0076] The spin-coating time is 3 minutes, and the rotation speed is 450 r / min; the concentration of the TiO2sol is 18 wt%;

[0077] The second drying treatment is performed at a temperature of 60 DEG C for 18 hours; the second calcination treatment is performed at a temperature of 350 DEG C for 6 hours;

[0078] (3) The TiO2-metal mesh composite film obtained in step (2) is immersed in a sodium hydroxide solution with a concentration of 8 mol / L for a hydrothermal modification treatment, and the super-hydrophilic oil-water separation film is obtained after cleaning treatment;

[0079] The hydrothermal modification treatment is performed at a temperature of 200 DEG C for 8 hours.

[0080] Example 3

[0081] The embodiment provides a super-hydrophilic oil-water separation film, and a preparation method of the super-hydrophilic oil-water separation film comprises the following steps:

[0082] (1) A copper mesh film is sequentially subjected to cleaning treatment, first drying treatment and first calcination treatment to obtain a film substrate;

[0083] The pore size of the copper mesh film is 400 meshes; the first calcination treatment is performed at a temperature of 750 DEG C for 8 hours;

[0084] (2) The TiO2sol is spin-coated on the film substrate obtained in step (1), and then a second drying treatment and a second calcination treatment are performed to obtain a TiO2-metal mesh composite film;

[0085] The spin-coating time is 2 minutes, and the rotation speed is 550 r / min; the concentration of the TiO2sol is 12 wt%;

[0086] The second drying treatment is performed at a temperature of 130 DEG C for 6 hours; the second calcination treatment is performed at a temperature of 450 DEG C for 4 hours;

[0087] (3) The TiO2-metal mesh composite film obtained in step (2) is immersed in a potassium hydroxide solution with a concentration of 12 mol / L for a hydrothermal modification treatment, and the super-hydrophilic oil-water separation film is obtained after cleaning treatment;

[0088] The hydrothermal modification treatment is performed at a temperature of 100 DEG C for 16 hours.

[0089] Example 4

[0090] This example provides a super-hydrophilic oil-water separation membrane, the preparation method of which differs from that of Example 1 only in that:

[0091] In this example, the pore size of the stainless steel mesh film in step (1) is adjusted to 100 mesh.

[0092] Example 5

[0093] This example provides a super-hydrophilic oil-water separation membrane, the preparation method of which differs from that of Example 1 only in that:

[0094] In this example, the pore size of the stainless steel mesh film in step (1) is adjusted to 800 mesh.

[0095] Example 6

[0096] This example provides a super-hydrophilic oil-water separation membrane, the preparation method of which differs from that of Example 1 only in that:

[0097] In this example, the time for the first calcination treatment in step (1) is adjusted to 2 h.

[0098] Example 7

[0099] This example provides a super-hydrophilic oil-water separation membrane, the preparation method of which differs from that of Example 1 only in that:

[0100] In this example, the time for the first calcination treatment in step (1) is adjusted to 10 h.

[0101] Example 8

[0102] This example provides a super-hydrophilic oil-water separation membrane, the preparation method of which differs from that of Example 1 only in that:

[0103] In this example, the time for the TiO2sol spin coating in step (2) is adjusted to 4 min.

[0104] Example 9

[0105] This example provides a super-hydrophilic oil-water separation membrane, the preparation method of which differs from that of Example 1 only in that:

[0106] In this example, the time for the TiO2sol spin coating in step (2) is adjusted to 0.5 min.

[0107] Example 10

[0108] The present example provides a super-hydrophilic oil-water separation membrane, the preparation method of the super-hydrophilic oil-water separation membrane is only different from that of example 1 in that:

[0109] In the present example, the concentration of the TiO2sol in step (2) is adjusted to 5wt%.

[0110] Example 11

[0111] The present example provides a super-hydrophilic oil-water separation membrane, the preparation method of the super-hydrophilic oil-water separation membrane is only different from that of example 1 in that:

[0112] In the present example, the concentration of the TiO2sol in step (2) is adjusted to 20wt%.

[0113] Example 12

[0114] The present example provides a super-hydrophilic oil-water separation membrane, the preparation method of the super-hydrophilic oil-water separation membrane is only different from that of example 1 in that:

[0115] In the present example, the time of the hydrothermal modification treatment in step (3) is adjusted to 4h.

[0116] Example 13

[0117] The present example provides a super-hydrophilic oil-water separation membrane, the preparation method of the super-hydrophilic oil-water separation membrane is only different from that of example 1 in that:

[0118] In the present example, the time of the hydrothermal modification treatment in step (3) is adjusted to 18h.

[0119] Example 14

[0120] The present example provides a super-hydrophilic oil-water separation membrane, the preparation method of the super-hydrophilic oil-water separation membrane is only different from that of example 1 in that:

[0121] In the present example, the concentration of the NaOH solution in step (3) is adjusted to 5mol / L.

[0122] Example 15

[0123] The present example provides a super-hydrophilic oil-water separation membrane, the preparation method of the super-hydrophilic oil-water separation membrane is only different from that of example 1 in that:

[0124] In the present example, the concentration of the NaOH solution in step (3) is adjusted to 18mol / L.

[0125] Comparative Example 1

[0126] The present example provides a super-hydrophilic oil-water separation membrane, the preparation method of the super-hydrophilic oil-water separation membrane is only different from that of example 1 in that:

[0127] The comparative example omits the first calcination process described in step (1).

[0128] Comparative Example 2

[0129] The comparative example provides a super-hydrophilic oil-water separation membrane, the preparation method of which is only different from that of Example 1 in that:

[0130] The comparative example omits the hydrothermal modification process described in step (3).

[0131] Performance test:

[0132] The super-hydrophilic oil-water separation membranes provided by the above examples and comparative examples are subjected to emulsion oil-water separation test, and the results are shown in Table 1.

[0133] The preparation method of the emulsion oil-water includes: mixing 1 g of peanut oil and 0.1 g of Span80 (sorbitan monooleate) in 1 L of deionized water, and obtaining a stable oil-in-water emulsion system after magnetic stirring for 1 h;

[0134] The emulsion oil-water separation test method includes: wetting the super-hydrophilic oil-water separation membrane, clamping it in two specially designed glass flange tubes, and first using sealant to ensure that the device does not leak. In the separation test, the prepared emulsion oil-water is directly poured onto the super-hydrophilic oil-water separation membrane, the permeated water is collected, and the over-water and oil-type separation is realized. The filtered mesh membrane is soaked in ethanol for 30 min, and is placed in air for 5 min before use.

[0135] Evaluation criteria: The COD (chemical oxygen demand in water) of the filtered liquid is used to indirectly determine the oil content in water, and the difference between the COD before and after filtration and the COD of the emulsion before filtration (i.e. separation efficiency) are used as evaluation. The higher the separation efficiency, the better the separation performance of the membrane.

[0136] In addition, the membranes provided by Example 1 and Comparative Example 2 are used to separate the emulsion oil-water, and the content change diagram of the oil in the separation process is as shown in Figure 2 ;

[0137] Figure 2 The black curve represents the emulsion oil-water; the red curve represents the separation process curve using the membrane provided by Comparative Example 2; and the blue curve represents the separation process curve using the membrane provided by Example 1.

[0138] Table 1

[0139] Efficiency of oil-water mixture separation (%) Flux (L·m -2 ·h -1 )]]> Example 1 81 31545 Example 2 67 36368 Example 3 72 32785 Example 4 60 38420 Example 5 77 20124 Example 6 65 32445 Example 7 21 31368 Example 8 77 31594 Example 9 72 31785 Example 10 75 32445 Example 11 77 31364 Example 12 3 37942 Example 13 78 30754 Example 14 73 31132 Example 15 70 31259 Comparative Example 1 52 38264 Comparative Example 2 55 33054

[0140] The following points can be known from the comprehensive analysis of Table 1:

[0141] (1) Comprehensive analysis of Examples 1-3 shows that the super-hydrophilic oil-water separation membrane provided by the application has a relatively high separation efficiency for emulsified oil, with a separation efficiency of more than 65%;

[0142] (2) Comprehensive analysis of Examples 1 and 4-5 shows that when the mesh number of the mesh increases, the mesh aperture gradually decreases, the flux decreases with the decrease of the mesh aperture, and the separation efficiency increases with the increase of the mesh aperture; when the mesh number is too large, the mesh aperture is small, which reduces the flux, thereby reducing the permeability of the mesh and increasing the separation time of the mesh; on the contrary, when the mesh number is too small, the mesh aperture is large, which increases the flux, thereby reducing the separation time of the mesh, but reducing the separation efficiency of the mesh;

[0143] (3) Comprehensive analysis of Examples 1, 6-7 and Comparative Example 1 shows that the membrane base calcination process affects the roughness of the membrane base, and further affects the loading effect of the TiO2 sol;

[0144] When the first calcination time is too long, the mesh becomes brittle and is prone to breakage, and the separation efficiency is significantly reduced; on the contrary, when the first calcination time is too short, it is difficult to form a rough morphology, thereby making it difficult for TiO2 to adhere, and reducing the separation efficiency;

[0145] Further, when the membrane base is not calcined, it is difficult for the TiO2 sol to be loaded on the surface of the steel mesh, and the absence of a rough structure will result in;

[0146] (4) Comprehensive analysis of Examples 1 and 8-11 shows that the TiO2 sol spin coating time and the TiO2 sol concentration both affect the coating thickness of TiO2 coated on the base membrane;

[0147] When the coating thickness of TiO2 on the surface of the base membrane increases, the rough morphology of the surface is covered by the TiO2 with a large thickness, thereby reducing the separation efficiency;

[0148] (5) Comprehensive analysis of Examples 1, 12-15 and Comparative Example 2 shows that the hydrothermal modification process affects the modification effect of the membrane, and even affects its demulsification function;

[0149] When the hydrothermal modification time is not enough, the linear TiO2 structure is reduced, which reduces the separation efficiency; when the hydrothermal modification time is too high, the linear TiO2 structure is not greatly affected, and the separation efficiency is also not greatly affected, thereby causing resource waste;

[0150] If the hydrothermal modification process is not performed, the mesh does not have a demulsification structure, and thus cannot separate emulsified oil, which greatly reduces the separation efficiency;

[0151] When the alkali concentration used in the hydrothermal modification treatment is too high, the TiO2 array is easy to fall off due to the too fast growth speed, thereby reducing the separation efficiency; when the alkali concentration is too low, the TiO2 growth speed is slow, the structure formation is affected, and the separation efficiency is reduced;

[0152] (6) According to Figure 2 It can be known that the TiO2-metal mesh composite film provided by the comparative example 2 cannot separate the oil droplets with small particle size, further proving that the hydrothermal modification process in the step (3) of the present application realizes the increase of the demulsification function in the separation film, that is, the separation film provided by the present application can effectively treat the emulsified oil which is difficult to separate.

[0153] In summary, the oil-water separation film provided by the present application has the super-hydrophilic and super-oleophobic properties, can treat the emulsified oil which is difficult to separate; and the oil-water separation film has good chemical stability and mechanical stability, and can be stably operated for a long time under different environmental conditions. In addition, the preparation method combines the physical and chemical methods, is simple to operate, does not need to add additional chemical reagents, is environmentally friendly, and has low energy consumption.

[0154] The applicant declares that the above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and it should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought out by those skilled in the art, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing a super-hydrophilic oil-water separation membrane, characterized in that, The preparation method comprises the following steps: (1) performing first calcination treatment on a metal mesh film to obtain a film base; (2) spin-coating TiO2 sol on the film base obtained in step (1), and then performing second drying treatment and second calcination treatment to obtain a TiO2-metal mesh composite film; (3) immersing the TiO2-metal mesh composite film obtained in step (2) in an alkali solution to perform hydrothermal modification treatment, so that the TiO2-metal mesh composite film has demulsification ability, and after cleaning treatment, the super-hydrophilic oil-water separation film is obtained; The alkali solution comprises a sodium hydroxide solution and / or a potassium hydroxide solution; the temperature of the hydrothermal modification treatment is 100-200 ℃, and the time is 8-16 h.

2. The method of claim 1, wherein the superhydrophilic oil-water separation membrane is prepared by the steps of: The metal mesh film in step (1) comprises any one of a stainless steel mesh film, a copper mesh film or a titanium mesh film.

3. The method of claim 2, wherein the superhydrophilic oil-water separation membrane is prepared by the steps of: The metal mesh film in step (1) is a stainless steel mesh film.

4. The method of claim 2, wherein the superhydrophilic oil-water separation membrane is prepared by the steps of: The pore size of the metal mesh film in step (1) is 200-600 mesh.

5. The method of claim 1, wherein the superhydrophilic oil-water separation membrane is prepared by the steps of: The temperature of the first calcination treatment in step (1) is 700-800 ℃.

6. The method of claim 5, wherein the superhydrophilic oil-water separation membrane is prepared by the steps of: The time of the first calcination treatment in step (1) is 4-8 h.

7. The method of claim 1, wherein the superhydrophilic oil-water separation membrane is prepared by the steps of: Before the first calcination treatment in step (1), cleaning treatment and first drying treatment are sequentially performed.

8. The method of claim 1, wherein the superhydrophilic oil-water separation membrane is prepared by the steps of: The spin-coating time in step (2) is 1-3 min.

9. The method of claim 8, wherein the superhydrophilic oil-water separation membrane is prepared by the steps of: The spin-coating speed in step (2) is 450-550 r / min.

10. The method of claim 1, wherein the superhydrophilic oil-water separation membrane is prepared by the steps of: The concentration of the TiO2 sol in step (2) is 6-18 wt%.

11. The method of claim 1, wherein the superhydrophilic oil-water separation membrane is prepared by the steps of: The temperature of the second drying treatment in step (2) is 60-130 ℃.

12. The method of claim 11, wherein the superhydrophilic oil-water separation membrane is prepared by the steps of: The time of the second drying treatment in step (2) is 6-18 h.

13. The method for preparing the superhydrophilic oil-water separation membrane according to claim 1, characterized in that, The temperature of the second calcination treatment in step (2) is 350-450 ℃.

14. The method of claim 13, wherein the superhydrophilic oil-water separation membrane is prepared by the steps of: The time of the second calcination treatment in step (2) is 2-6 h.

15. The method for preparing the superhydrophilic oil-water separation membrane according to claim 1, characterized in that, The concentration of the alkali solution in step (3) is 8-12 mol / L.

16. A superhydrophilic oil-water separation membrane, characterized in that, The super-hydrophilic oil-water separation film is obtained by the preparation method in any one of claims 1-15.

17. Use of the superhydrophilic oil-water separation membrane according to claim 16, characterized in that, The super-hydrophilic oil-water separation film is used for separating an oil-water mixture. The particle size of the oil in the oil-water mixture is 0.1-100 μm.

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