Preparation method of waste biomass-based janus oil-water separation membrane and application of waste biomass-based janus oil-water separation membrane in emulsion separation

Abstract

The application belongs to the technical field of functional materials, and relates to a preparation method of a waste biomass-based Janus oil-water separation membrane, which comprises the following steps: soaking waste qualitative filter paper in 1-10wt% dilute hydrochloric acid for 6-36 hours, cleaning the qualitative filter paper multiple times with ethanol and ionized water, and vacuum drying the qualitative filter paper at 50 DEG C for 4 hours to obtain a cellulose membrane CM; suspending and placing the cellulose membrane CM in a 0.5-5g / L DA-HCl solution with a pH of 8.5, and soaking the cellulose membrane CM at 25 DEG C for 2-48 hours to obtain a dopamine-modified membrane material PDA / CM, which is vacuum dried at 50 DEG C for 12 hours; electrospinning hydrophobic PVDF on the surface of the super-hydrophilic PDA / CM, and vacuum drying at 25 DEG C to obtain the Janus oil-water separation membrane. The prepared membrane is applied to emulsion separation. The application replaces artificial polymers with widely-sourced, environment-degradable and easily-wet-modified biomass, solves the problems of difficult degradation, low permeation flux, secondary pollution caused by waste, poor repeatability and the like of artificial high molecules such as PVDF, and has the characteristics of efficient utilization of biomass resources, environmental friendliness and scale production.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, and relates to composite membranes, particularly to a method for preparing a waste biomass-based Janus oil-water separation membrane and its application in emulsion separation. Background Technology

[0002] Leaked crude oil can rapidly spread into a dense oil film in ocean waters, inhibiting the reoxygenation of the water, reducing the oxygen content of polluted sea areas, and disrupting the marine ecological balance. The oil in oily wastewater cannot be burned and is highly toxic. If it is not effectively treated, it will not only have a serious impact on the aquatic environment, but also waste oil resources.

[0003] Specialized wetting materials, due to their unique selective wetting properties, show promising application prospects for the efficient and selective separation of oil-water mixtures. However, for large-scale oily wastewater treatment, the practical application of materials such as ceramic membranes, synthetic polymer membranes, aerogels, porous foams, and metal mesh membranes is limited by factors such as unsustainable raw materials, high cost, poor flexibility, poor recyclability, and poor durability. Biomass, a sustainable green resource in nature, possesses excellent properties such as wide availability, biodegradability, low toxicity, and abundant active functional groups, making it an ideal material to replace the substrate of oil / water mixture separation materials.

[0004] Therefore, using waste biomass cellulose as a substrate, a superhydrophilic polydopamine / cellulose membrane (PDA / CM) was obtained after dopamine modification. Polyethylene terephthalate (PVDF) fiber membranes were then electrospun on the superhydrophilic PDA / CM surface to form hydrophobic PVDF, ultimately yielding a Janus membrane (PVDF / PDA / CM) with asymmetric wetting properties, which was applied to the separation of water-in-oil (W / O) and oil-in-water (O / W) emulsions. This invention uses waste filter paper as raw material, extracts biomass cellulose from it, and combines electrospinning and in-situ modification techniques to obtain a Janus membrane with asymmetric wetting properties. This not only proposes a highly efficient membrane material for separating water-in-oil and oil-in-water emulsions but also provides an effective strategy for the resource recycling of waste biomass. Summary of the Invention

[0005] To address the shortcomings of the existing technology, the present invention discloses a method for preparing a waste biomass-based Janus oil-water separation membrane. This material uses waste filter paper as raw material and combines electrospinning technology to electrospin a hydrophobic polyethylene terephthalate (PVDF) fiber membrane onto the surface of a superhydrophilic polydopamine / cellulose (PDA / CM) membrane, thereby achieving control over the material's wettability and enabling its application in the separation of oil-in-water and water-in-oil emulsions.

[0006] Technical solution

[0007] A method for preparing a waste biomass-based Janus oil-water separation membrane includes the following steps:

[0008] a) After soaking the waste qualitative filter paper in 1-10 wt% dilute hydrochloric acid for 6-36 h, preferably 6 wt% dilute hydrochloric acid for 24 h, it is washed multiple times with ethanol and deionized water, and then vacuum dried at 50 ℃ for 4 h to obtain cellulose membrane CM.

[0009] b) The fiber membrane CM is suspended in a 0.5-5 g / L DA-HCl solution with pH 8.5, preferably 2 g / L, and soaked at 25°C for 2-48 h, preferably 24 h. The resulting dopamine-modified membrane material PDA / CM is then vacuum dried at 50°C for 12 h.

[0010] c) Electrospin hydrophobic PVDF onto the surface of superhydrophilic PDA / CM and vacuum dry at 25°C to obtain waste biomass-based Janus oil-water separation membrane (PVDF / PDA / CM).

[0011] In a preferred embodiment of the present invention, the electrospinning described in step c) is electrospinning, specifically comprising the following steps: dissolving 0.4–8 g of PVDF membrane in 44.2 g of a mixed solution of N'N-dimethylformamide / acetone with a mass ratio of 1:9–9:1 at 20–80°C to form an electrospinning precursor solution, preferably at 30°C, 3.6 g, and a mass ratio of 4:1; injecting the precursor solution into a 10 mL syringe, setting the spinning rate to 0.010–0.1 mL / min, preferably 0.035 mL / min, fixing the distance between the injection head and the receiving electrode to 5–25 cm, preferably 10 cm, and setting the spinning voltage to 10–25 kV, preferably 15 kV.

[0012] The waste biomass-based Janus oil-water separation membrane prepared according to the method of the present invention has asymmetric wetting properties.

[0013] Another objective of this invention is to apply the prepared waste biomass-based Janus oil-water separation membrane to emulsion separation, wherein the emulsion includes water-in-oil and oil-in-water emulsions.

[0014] The oil-water mixture is poured into a filtration and separation device. O / W emulsions are separated under gravity, and W / O emulsions are separated under a pressure of 0.5 MPa. Surface-affected liquids pass smoothly through the filter membrane, while surface-repellent liquids are blocked. n R(%) represents the separation efficiency of the emulsion. When n is 1, R1(%) is the separation efficiency of the O / W emulsion; when n is 2, R2(%) is the separation efficiency of the W / O emulsion. R is calculated according to formula (1). n (%):

[0015] (1)

[0016] C0 and C1 represent the content of surface protective liquid in the feed liquid and the collected liquid, respectively.

[0017] F n (L m -2 h -1 bar -1 F1 represents the emulsion separation flux per unit pressure. When n is 1, F1 (L m) -2 h -1 bar -1 ) represents the separation flux of the O / W emulsion per unit pressure; when n is 2, F2 (L m) -2 h -1 bar -1 F represents the separation flux of the W / O emulsion per unit pressure. Calculate F according to formula (2). n (L m -2 h -1 bar -1 ):

[0018] (2)

[0019] In the formula, V (L) is the volume of filtrate, and A (m³) is the volume of filtrate 2 ) represents the effective filtration area, Δt (h) represents the infiltration time, and P (bar) represents the applied pressure.

[0020] The dichloromethane, trifluoroacetic acid, dopamine hydrochloride (DA-HCl), ethylenediamine (EDA), triethylamine (C6H15N), hexadecane, toluene, chloroform, and diesel oil used in this invention were sourced from Sinopharm Chemical Reagent Co., Ltd. The qualitative filter paper (medium speed, pore size 15-20 μm, thickness 340±20 μm) was sourced from Hangzhou Special Paper Co., Ltd. The PVDF membrane was sourced from Tianjin Jinteng Equipment Co., Ltd.

[0021] The features of this invention are:

[0022] (1) Using readily available waste filter membranes in the laboratory as the source of biomass cellulose membranes, high-value cellulose membranes were prepared. Janus membranes with asymmetric wetting properties were prepared by hydrophilic modification and electrospinning technology. The preparation process is simple, the production cost is low and the environment is environmentally friendly. This realizes the efficient utilization of biomass resources and can provide a new method for synthesizing efficient environmental oily pollutant wastewater treatment materials.

[0023] (2) Using common PVDF membranes as raw materials, electrospun PVDF fiber membranes were constructed on the surface of hydrophilic cellulose. A biomass-based Janus membrane separation material with strong hydrophobicity and superhydrophilic wettability was designed and prepared. The wettability conversion and separation of water-in-oil and oil-in-water emulsions can be achieved by membrane flipping.

[0024] (3) The obtained Janus oil-water separation membrane can achieve high-efficiency separation of oil-in-water and water-in-oil emulsions, maintains stable separation efficiency after repeated use, and still exhibits good separation performance under harsh environmental conditions such as acid and alkalinity.

[0025] Beneficial effects

[0026] This invention discloses a method for preparing a waste biomass-based Janus oil-water separation membrane. Waste biomass cellulose is used as a substrate, and after dopamine modification, a superhydrophilic polydopamine / cellulose membrane (PDA / CM) is obtained. A polyethylene terephthalate (PVDF) fiber membrane is electrospun on the superhydrophilic PDA / CM surface to form a hydrophobic PVDF, ultimately yielding a Janus membrane (PVDF / PDA / CM) with asymmetric wetting properties, applicable to the separation of water-in-oil (W / O) and oil-in-water (O / W) emulsions. The obtained material exhibits high separation efficiency, stable superhydrophobicity, good recyclability, and a simple preparation process. The in-situ modification and electrospinning techniques involved are simple in synthesis steps and possess sustainable and recyclable characteristics. This invention replaces artificial polymers with biomass, which is widely available, environmentally degradable, sustainable, and easy to wet and modify. It studies the application of biomass in the treatment of oily wastewater and solves the problems of artificial polymers such as PVDF being difficult to degrade, having low permeability, generating secondary pollution from waste, and having poor reproducibility. It has the characteristics of efficient utilization of biomass resources, environmental friendliness, and the ability to be produced on a large scale. Attached Figure Description

[0027] Figure 1 SEM images of the CM membrane (a-a2), Janus-PDA / CM surface (b-b2), and Janus-PVDF surface (c-c2) at different scales;

[0028] Figure 2 The wettability of Janus membranes: water droplets and oil droplets on the PVDF layer surface (ab); water droplets and oil droplets on the PDA / CM surface (cd); the rolling state of oil droplets on the PDA / CM surface in water (e);

[0029] Figure 3 Separation flux (a) and separation efficiency (b) of surfactant-stabilized water-in-hexadecane (H / W), water-in-toluene (T / W), water-in-chloroform (C / W), and water-in-diesel (D / W) emulsions.

[0030] Figure 4 Separation flux (a) and separation efficiency (b) of surfactant-stabilized cetane-in-water (W / H), toluene-in-water (W / T), chloroform-in-water (W / C), and diesel-in-water (W / D) emulsions. Detailed Implementation

[0031] The present invention will be described in detail below with reference to embodiments, so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following embodiments.

[0032] Unless otherwise specified, the terms used herein (including technical terms) shall be interpreted as having the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It will also be understood that the terms used herein shall be interpreted as having the same meaning as they have in the context of this specification and related art, and shall not be interpreted in an idealized or excessive manner, unless specifically defined herein.

[0033] Example 1

[0034] A method for preparing a waste biomass-based Janus oil-water separation membrane includes the following steps:

[0035] a) After soaking the waste qualitative filter paper in 1 wt% dilute hydrochloric acid for 6 h, it was washed multiple times with ethanol and deionized water, and dried under vacuum at 50 ℃ for 4 h to obtain cellulose membrane (CM).

[0036] b) The fiber membrane CM was suspended in a 0.5 g / L DA-HCl solution with pH=8.5 and soaked at 25 ℃ for 2 h. The resulting dopamine modified membrane material PDA / CM was vacuum dried at 50 ℃ for 12 h for later use.

[0037] c) A hydrophobic PVDF membrane was constructed on the superhydrophilic PDA / CM surface using electrospinning technology. The specific steps are as follows: 0.4 g of PVDF membrane was dissolved in 44.2 g of a 1:9 N'N-dimethylformamide / acetone mixed solution at 20 °C to form an electrospinning precursor solution. The precursor solution was injected into a 10 mL syringe, and the spinning rate was set to 0.010 mL / min. The distance between the injection head and the receiving electrode was fixed at 5 cm, and the spinning voltage was 10 kV. The membrane material PVDF / PDA / CM was obtained by vacuum drying at 25 °C.

[0038] The oil-water mixture is poured into a filtration and separation device, where the O / W emulsion is separated under gravity and the W / O emulsion is separated under a pressure of 0.5 MPa.

[0039] The prepared Janus membrane achieved a permeation flux of 9400 L / m for hexadecane (H / W), toluene (T / W), chloroform (C / W), and diesel (D / W) emulsions. -2 h -1 bar -1 9640 L m -2 h-1 bar -1 9350 L m -2 h -1 bar -1 and 9040 L m -2 h -1 bar -1 .

[0040] The Janus membrane achieved separation efficiencies of 75%, 77%, 76%, and 67% for H / W, T / W, C / W, and D / W emulsions, respectively. The prepared Janus membrane also achieved permeate fluxes of 8060 L / m³ for cetane-in-water (W / H), toluene-in-water (W / T), chloroform-in-water (W / C), and diesel-in-water (W / D) emulsions. -2 h -1 bar -1 7330 L m -2 h -1 bar -1 3510 L m -2 h -1 bar -1 and 1660 L m -2 h -1 bar -1 .

[0041] Janus membranes achieved separation efficiencies of 75%, 67%, 66%, and 63% for W / H, W / T, W / C, and W / D emulsions, respectively.

[0042] Example 2

[0043] A method for preparing a waste biomass-based Janus oil-water separation membrane includes the following steps:

[0044] a) After soaking the waste qualitative filter paper in 5 wt% dilute hydrochloric acid for 16 h, it was washed multiple times with ethanol and deionized water, and dried under vacuum at 50 ℃ for 4 h to obtain cellulose membrane (CM).

[0045] b) The fiber membrane CM was suspended in a 1 g / L DA-HCl solution with pH=8.5 and soaked at 25℃ for 4 h. The resulting dopamine modified membrane material PDA / CM was vacuum dried at 50℃ for 12 h for later use.

[0046] c) A hydrophobic PVDF membrane was constructed on the superhydrophilic PDA / CM surface using electrospinning technology. The specific steps are as follows: 4 g of PVDF membrane was dissolved in 44.2 g of a 2:8 N'N-dimethylformamide / acetone mixed solution at 40 °C to form an electrospinning precursor solution. The precursor solution was injected into a 10 mL syringe, and the spinning rate was set to 0.015 mL / min. The distance between the injection head and the receiving electrode was fixed at 10 cm, and the spinning voltage was 12.5 kV. The membrane material PVDF / PDA / CM was obtained by vacuum drying at 25 °C.

[0047] The oil-water mixture is poured into a filtration and separation device, where the O / W emulsion is separated under gravity and the W / O emulsion is separated under a pressure of 0.5 MPa.

[0048] The prepared Janus membrane achieved a permeation flux of 11400 L / m for hexadecane (H / W), toluene (T / W), chloroform (C / W), and diesel (D / W) emulsions. -2 h -1 bar -1 10340 L m -2 h -1 bar -1 10650 L m -2 h -1 bar -1 and 9440 L m -2 h -1 bar -1 .

[0049] The Janus membrane achieved separation efficiencies of 78%, 83%, 82%, and 71% for H / W, T / W, C / W, and D / W emulsions, respectively. The prepared Janus membrane also achieved permeate fluxes of 9160 L / m³ for cetane-in-water (W / H), toluene-in-water (W / T), chloroform-in-water (W / C), and diesel-in-water (W / D) emulsions. -2 h -1 bar -1 8050 L m -2 h -1 bar -1 4110 L m -2 h -1 bar -1 and 1950 L m -2 h -1 bar -1 .

[0050] Janus membranes achieved separation efficiencies of 90%, 84%, 88%, and 83% for W / H, W / T, W / C, and W / D emulsions, respectively.

[0051] Example 3

[0052] A method for preparing a waste biomass-based Janus oil-water separation membrane includes the following steps:

[0053] a) The waste qualitative filter paper was soaked in 6 wt% dilute hydrochloric acid for 24 h, washed repeatedly with ethanol and deionized water, and dried under vacuum at 50 ℃ for 4 h to obtain cellulose membrane (CM).

[0054] b) The fiber membrane CM was suspended in a 2 g / L DA-HCl solution at pH=8.5 and soaked at 25 ℃ for 24 h. The resulting dopamine modified membrane material PDA / CM was vacuum dried at 50 ℃ for 12 h for later use.

[0055] c) A hydrophobic PVDF membrane was constructed on the superhydrophilic PDA / CM surface using electrospinning technology. The specific steps are as follows: 3.6 g of PVDF membrane was dissolved in 44.2 g of a 4:1 N'N-dimethylformamide / acetone mixed solution at 30 °C to form an electrospinning precursor solution. The precursor solution was injected into a 10 mL syringe, and the spinning rate was set to 0.035 mL / min. The distance between the injection head and the receiving electrode was fixed at 10 cm, and the spinning voltage was 15 kV. The membrane material PVDF / PDA / CM was obtained by vacuum drying at 25 °C.

[0056] The oil-water mixture is poured into a filtration and separation device, where the O / W emulsion is separated under gravity and the W / O emulsion is separated under a pressure of 0.5 MPa.

[0057] The prepared Janus membrane achieved a permeation flux of 14500 L / m for hexadecane (H / W), toluene (T / W), chloroform (C / W), and diesel (D / W) emulsions. -2 h -1 bar -1 13695 L m -2 h -1 bar -1 12950 L m -2 h -1 bar -1 and 9860 L m -2 h -1 bar -1 .

[0058] Janus membranes exhibit high separation efficiency for H / W, T / W, C / W, and D / W emulsions, with efficiency exceeding 99%. The prepared Janus membranes achieved permeation fluxes of 9877 L / m for cetane-in-water (W / H), toluene-in-water (W / T), chloroform-in-water (W / C), and diesel-in-water (W / D) emulsions. -2 h -1 bar -1 8590 L m -2 h -1 bar -1 4719 L m -2 h -1 bar -1 and 2510 L m -2 h -1 bar -1 .

[0059] Janus membranes achieve separation efficiencies of over 98.8% for W / H, W / T, W / C, and W / D emulsions.

[0060] Example 4

[0061] A method for preparing a waste biomass-based Janus oil-water separation membrane includes the following steps:

[0062] a) After soaking the waste qualitative filter paper in 8 wt% dilute hydrochloric acid for 24 h, it was washed multiple times with ethanol and deionized water, and dried under vacuum at 50 ℃ for 4 h to obtain cellulose membrane (CM).

[0063] b) The fiber membrane CM was suspended in a 3 g / L DA-HCl solution at pH=8.5 and soaked at 25 ℃ for 36 h. The resulting dopamine modified membrane material PDA / CM was vacuum dried at 50 ℃ for 12 h for later use.

[0064] c) A hydrophobic PVDF membrane was constructed on the superhydrophilic PDA / CM surface using electrospinning technology. The specific steps are as follows: 4.8 g of PVDF membrane was dissolved in 44.2 g of a 6:4 N'N-dimethylformamide / acetone mixed solution at 50 °C to form an electrospinning precursor solution. The precursor solution was injected into a 10 mL syringe, and the spinning rate was set to 0.05 mL / min. The distance between the injection head and the receiving electrode was fixed at 15 cm, and the spinning voltage was 20 kV. The membrane material PVDF / PDA / CM was obtained by vacuum drying at 25 °C.

[0065] The oil-water mixture is poured into a filtration and separation device, where the O / W emulsion is separated under gravity and the W / O emulsion is separated under a pressure of 0.5 MPa.

[0066] The prepared Janus membrane achieved a permeation flux of 13600 L / m for hexadecane (H / W), toluene (T / W), chloroform (C / W), and diesel (D / W) emulsions. -2 h -1 bar -1 11450 L m -2 h -1 bar -1 10330 L m -2 h -1 bar -1 and 9690 L m -2 h -1 bar -1 .

[0067] The Janus membrane achieved separation efficiencies of 82%, 88%, 87%, and 73% for H / W, T / W, C / W, and D / W emulsions, respectively. The prepared Janus membrane also achieved permeate fluxes of 9550 L / m³ for cetane-in-water (W / H), toluene-in-water (W / T), chloroform-in-water (W / C), and diesel-in-water (W / D) emulsions. -2 h -1 bar -1 8210 L m -2 h -1 bar -1 4650 L m -2 h -1 bar -1 and 2300 L m -2 h -1 bar -1 .

[0068] Janus membranes achieved separation efficiencies of 95%, 91%, 93%, and 92% for W / H, W / T, W / C, and W / D emulsions, respectively.

[0069] Example 5

[0070] A method for preparing a waste biomass-based Janus oil-water separation membrane includes the following steps:

[0071] a) After soaking the waste qualitative filter paper in 10 wt% dilute hydrochloric acid for 36 h, it was washed multiple times with ethanol and deionized water, and dried under vacuum at 50 ℃ for 4 h to obtain cellulose membrane (CM).

[0072] b) The fiber membrane CM was suspended in a 5 g / L DA-HCl solution at pH=8.5 and soaked at 25 ℃ for 48 h. The resulting dopamine modified membrane material PDA / CM was vacuum dried at 50 ℃ for 12 h for later use.

[0073] c) A hydrophobic PVDF membrane was constructed on the superhydrophilic PDA / CM surface using electrospinning technology. The specific steps are as follows: 8 g of PVDF membrane was dissolved in 44.2 g of a 9:1 N'N-dimethylformamide / acetone mixed solution at 80 °C to form an electrospinning precursor solution. The precursor solution was injected into a 10 mL syringe, and the spinning rate was set to 0.1 mL / min. The distance between the injection head and the receiving electrode was fixed at 25 cm, and the spinning voltage was 25 kV. The membrane material PVDF / PDA / CM was obtained by vacuum drying at 25 °C.

[0074] The oil-water mixture is poured into a filtration and separation device, where the O / W emulsion is separated under gravity and the W / O emulsion is separated under a pressure of 0.5 MPa.

[0075] The prepared Janus membrane achieved a permeation flux of 12400 L / m for hexadecane (H / W), toluene (T / W), chloroform (C / W), and diesel (D / W) emulsions. -2 h -1 bar -1 10040 L m -2 h -1 bar -1 10850 L m -2 h -1 bar -1 and 9340 L m -2 h -1 bar -1 .

[0076] The Janus membrane achieved separation efficiencies of 80%, 82%, 84%, and 70% for H / W, T / W, C / W, and D / W emulsions, respectively. The prepared Janus membrane also achieved permeate fluxes of 9580 L / m³ for cetane-in-water (W / H), toluene-in-water (W / T), chloroform-in-water (W / C), and diesel-in-water (W / D) emulsions. -2 h -1 bar -1 8300 L m -2 h -1 bar -1 4650 L m -2 h -1 bar -1 and 2350 L m -2 h -1 bar -1 .

[0077] The Janus membrane achieved separation efficiencies of 95.5%, 92%, 93%, and 94% for W / H, W / T, W / C, and W / D emulsions, respectively.

[0078] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a waste biomass-based Janus oil-water separation membrane, characterized in that, The method comprises the following steps: a) soaking the waste qualitative filter paper in 1-10 wt% dilute hydrochloric acid for 6-36 h, washing with ethanol and ionized water for multiple times, and vacuum drying at 50°C for 4 h to obtain a cellulose membrane CM; b) suspending the cellulose membrane CM in a 0.5-5 g / L DA-HCl solution with a pH of 8.5 and soaking at 25°C for 2-48 h to obtain a dopamine-modified membrane material PDA / CM, which is vacuum dried at 50°C for 12 h; c) electrospinning hydrophobic PVDF on the super-hydrophilic PDA / CM surface and vacuum drying at 25°C to obtain the Janus oil-water separation membrane.

2. The method for preparing the waste biomass-based Janus oil-water separation membrane according to claim 1, characterized in that: In step a), the waste qualitative filter paper is soaked in 6 wt% dilute hydrochloric acid for 24 h.

3. The method for preparing the waste biomass-based Janus oil-water separation membrane according to claim 1, characterized in that: In step b), the cellulose membrane CM is suspended in a 2 g / L DA-HCl solution with a pH of 8.5 and soaked at 25°C for 24 h.

4. The method for preparing the waste biomass-based Janus oil-water separation membrane according to claim 1, characterized in that, In step c), electrospinning, specifically: dissolving 3.6 g of PVDF membrane in 44.2 g of N’N-dimethylformamide / acetone mixed solution with a mass ratio of 4:1 to form an electrospinning precursor solution at 30°C; setting the spinning rate to 0.035 mL / min, fixing the distance between the injection head and the receiving electrode to 10 cm, and setting the spinning voltage to 15 kV.

5. The method for preparing the waste biomass-based Janus oil-water separation membrane according to claim 4, characterized in that: In step c), electrospinning, specifically: dissolving 3.6 g of PVDF membrane in 44.2 g of N’N-dimethylformamide / acetone mixed solution with a mass ratio of 4:1 to form an electrospinning precursor solution at 30°C; setting the spinning rate to 0.035 mL / min, fixing the distance between the injection head and the receiving electrode to 10 cm, and setting the spinning voltage to 15 kV.

6. The method for preparing the waste biomass-based Janus oil-water separation membrane according to claim 4, characterized in that:

7. The waste biomass-based Janus oil-water separation membrane prepared by the method of any one of claims 1-6. The Janus oil-water separation membrane has asymmetric wetting properties.

8. The waste biomass-based Janus oil-water separation membrane according to claim 7, characterized in that: It is applied to emulsion separation.

9. Use of the waste biomass-based Janus oil-water separation membrane according to claim 7, characterized in that: The emulsion includes water-in-oil and oil-in-water emulsion.

10. Use of a waste biomass-based Janus oil-water separation membrane according to claim 9, characterized in that: The emulsion includes water-in-oil and oil-in-water emulsion.

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