Method for preparing janus cellulose membranes based on waste plastics and its application in emulsion separation

Abstract

The application belongs to the technical field of functional materials, and relates to a preparation method of Janus cellulose membrane based on waste plastic, which comprises the following steps: soaking waste qualitative filter paper in 1-10wt% dilute hydrochloric acid for 12-36 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 immersing 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 super-hydrophilic dopamine modified membrane PDA / CM, which is vacuum dried at 50 DEG C for 12 hours; then electrospinning hydrophobic PET on the surface of the super-hydrophilic dopamine modified membrane PDA / CM, and vacuum drying the super-hydrophilic dopamine modified membrane PDA / CM at 50 DEG C, so that the Janus cellulose membrane based on waste plastic is obtained. The prepared functional membrane is applied to emulsion separation. The application has the characteristics of sustainability and cyclic regeneration.

Description

Technical Field

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

[0002] Currently, common oil-water separation methods include adsorption, electrostatic separation, coalescence separation, biodegradation, and chemical treatment. However, these methods all have certain drawbacks. For example, adsorption has limited capacity, high operating costs, and cannot be recycled, resulting in material waste; electrostatic separation requires external power equipment, leading to high energy consumption; and biodegradation requires harsh conditions, has a long cycle time, and low separation efficiency. Furthermore, due to the low interfacial tension between water and oil, surfactant-stabilized oil / water emulsions are droplets with a diameter of less than 20 μm, making them difficult to separate using traditional techniques. To improve emulsion separation efficiency, many interfacial materials with different surface wettability have attracted considerable attention due to their excellent separation performance. These high-performance materials possess abundant porosity and tortuous porous channels, enabling the coalescence of tiny emulsion droplets, but they still suffer from low separation efficiency and low separation flux. Therefore, there is an urgent need to develop more functional separation materials with ultra-high permeability and high efficiency.

[0003] Currently developed technologies allow the use of waste plastics as raw materials to prepare functional materials with different wetting properties, which can be applied to the field of oil-water separation.

[0004] Therefore, using waste cellulose as the membrane matrix, a superhydrophilic polydopamine / cellulose membrane (PDA / CM) is obtained after dopamine modification. A polyethylene terephthalate (PET) fiber membrane electrospinning solution is prepared using waste cola bottles as raw materials. PET is then electrospun on the superhydrophilic PDA / CM surface to form a hydrophobic PET, ultimately yielding a Janus membrane (PET / PDA / CM) with asymmetric wetting properties, which is applied to the separation of water-in-oil (W / O) and oil-in-water (O / W) emulsions. This invention uses waste cola bottles as raw materials, combining 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 plastics. Summary of the Invention

[0005] To address the shortcomings of the existing technology, the present invention discloses a method for preparing Janus cellulose membrane based on waste plastic and its application in emulsion separation. This material uses waste cola bottle plastic as raw material, and combines electrospinning technology to electrospin superhydrophobic polyethylene terephthalate (PET) fibers onto the surface of a superhydrophilic polydopamine / cellulose membrane (PDA / CM), thereby achieving control over the material's wettability and applying it to the field of oil-in-water and water-in-oil emulsion separation.

[0006] Technical solution

[0007] A method for preparing a Janus cellulose membrane based on waste plastic includes the following steps:

[0008] a) After soaking the waste qualitative filter paper in 1-10 wt% dilute hydrochloric acid for 12-36 hours, preferably 6 wt% dilute hydrochloric acid for 24 hours, it is washed multiple times with ethanol and deionized water, and then vacuum dried at 50°C for 4 hours to obtain cellulose membrane CM.

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

[0010] c) Electrospin hydrophobic PET onto the surface of a superhydrophilic dopamine-modified membrane (PDA / CM) and vacuum dry at 50°C to obtain a Janus cellulose membrane (PET / PDA / CM) based on waste plastic.

[0011] In a preferred embodiment of the present invention, the electrospinning described in step c) is electrospinning, specifically comprising the following steps: dissolving 0.5–5 g of PET plastic sheet in 100 mL of a trifluoroacetic acid / dichloromethane mixed solution with a volume ratio of 1:9–9:1 at 20–50 °C to form an electrospinning precursor solution, preferably 1.5 g at 25 °C with a volume ratio of 3:7; injecting the precursor solution into a 10 mL syringe, setting the spinning rate to 0.010–0.1 mL / min, preferably 0.037 mL / min, fixing the distance between the injection head and the receiving electrode to 12–25 cm, preferably 20 cm, and setting the spinning voltage to 15–25 kV, preferably 17 kV.

[0012] The Janus cellulose membrane material based on waste plastic prepared according to the method of the present invention has asymmetric wetting properties.

[0013] Another objective of this invention is to apply the prepared Janus cellulose membrane (PET / PDA / CM) based on waste plastics 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 R1(%) represents the separation efficiency of the emulsion. When n is 1, R1(%) represents the separation efficiency of the O / W emulsion; when n is 2, R2(%) represents 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 liquid 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), n-heptane, n-hexane, petroleum ether, and chloroform used in this invention were from Sinopharm Chemical Reagent Co., Ltd. The qualitative filter paper (medium speed, pore size 15-20 μm, thickness 340±20 μm) was from Hangzhou Special Paper Co., Ltd. The discarded cola plastic bottles used were collected from local supermarkets.

[0021] The features of this invention are:

[0022] (1) Using common waste qualitative filter paper as raw material, a high-value cellulose membrane was prepared. Janus membrane with asymmetric wetting properties was prepared by hydrophilic modification and electrospinning technology. It has the characteristics of simple preparation process, low production cost and environmental friendliness. It not only realizes the resource utilization of waste biomass, but also develops a high-performance oil-water mixture separation membrane material.

[0023] (2) Using common waste cola bottles as raw materials, electrospun PET fiber membranes are constructed on the surface of hydrophilic cellulose to form Janus separation membranes with a stacked structure. This provides a high-value-added strategy for the resource utilization of waste plastics and has the advantages of being environmentally friendly and sustainable.

[0024] (3) The prepared Janus separation membrane material can achieve on-demand separation of surfactant-stable oil-in-water emulsions and water-in-oil emulsions by membrane flipping. The asymmetric wettability, high emulsion separation performance, low cost and ease of use of the Janus separation membrane give it a great advantage in oil-water separation efficiency.

[0025] Beneficial effects

[0026] This invention discloses a method for preparing Janus cellulose membranes based on waste plastics and its emulsion separation. Waste cellulose is used as the membrane matrix, and after modification with dopamine, a superhydrophilic polydopamine / cellulose membrane (PDA / CM) is obtained. A PET electrospinning solution is prepared using waste cola bottles as raw materials. PET is electrospun onto the surface of the superhydrophilic PDA / CM to form hydrophobic PET, ultimately obtaining a Janus membrane with asymmetric wetting properties. It exhibits good mechanical properties, stable chemical properties, excellent hydrophobic effect, good reusability, and convenient operation. The in-situ modification and electrospinning techniques involved are simple in synthesis steps and have sustainable and recyclable characteristics. This invention uses common waste plastics as raw materials to recycle environmental waste resources, not only solving environmental pollution problems to a certain extent but also preparing functionalized separation materials for separating oil-water waste liquids, achieving the goal of "treating waste with waste." Attached Figure Description

[0027] Figure 1 SEM images of cross sections (df) of CM film (a-a1), Janus-PDA / CM film (b-b1), Janus-PET film (c-c1), and Janus film at different scales;

[0028] Figure 2 The wettability of Janus membranes: water and oil droplets on the PET layer surface (ab); water 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 3Separation efficiency (a) and separation flux (b) of surfactant-stabilized petroleum ether (T / W), n-hexane (X / W), n-heptane (P / W), and chloroform (L / W) emulsions.

[0030] Figure 4 Separation efficiency (a) and separation flux (b) of surfactant-stabilized petroleum ether-in-water (W / T), n-hexane-in-water (W / X), n-heptane-in-water (W / P), and chloroform-in-water (W / L) 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 Janus cellulose membrane based on waste plastic includes the following steps:

[0035] a) After soaking the waste qualitative filter paper in 1 wt% dilute hydrochloric acid for 12 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 PET membrane was constructed on the surface of a superhydrophilic PDA / CM using electrospinning technology. The specific steps are as follows: 0.5 g of PET plastic sheet was dissolved in 100 mL of a 1:9 trifluoroacetic acid / dichloromethane 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 12 cm, and the spinning voltage was 15 kV. The membrane material PET / PDA / CM was obtained by vacuum drying at 50 °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 Janus membrane achieved separation efficiencies of 77%, 75%, 76%, and 69% for petroleum ether (T / W), n-hexane (X / W), n-heptane (P / W), and chloroform (L / W) in water, respectively.

[0040] Janus membranes achieved permeation fluxes of 8320 L / m for T / W, X / W, P / W, and L / W emulsions, respectively. -2 h -1 bar -1 6795 Lm -2 h -1 bar -1 8750 L m -2 h -1 bar -1 and 7805 L m -2 h -1 bar -1 The separation efficiencies for petroleum ether-in-water (W / T), n-hexane-in-water (W / X), n-heptane-in-water (W / P), and chloroform-in-water (W / L) emulsions were 79%, 72%, 64%, and 68%, respectively.

[0041] The Janus membrane had a permeation flux of 1037 L / m for W / T, W / X, W / P, and W / L emulsions, respectively. -2 h -1 bar -1 869 Lm -2 h -1 bar -1 850 L m -2 h -1 bar -1 640L m -2 h -1 bar -1 .

[0042] Example 2

[0043] A method for preparing a Janus cellulose membrane based on waste plastic includes the following steps:

[0044] a) After soaking the waste qualitative filter paper in 2 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).

[0045] b) The fiber membrane CM was suspended in a 2.5 g / L DA-HCl solution with 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.

[0046] c) A hydrophobic PET membrane was constructed on the surface of a superhydrophilic PDA / CM using electrospinning technology. The specific steps are as follows: 4.5 g of PET plastic sheet was dissolved in 100 mL of a 5:5 trifluoroacetic acid / dichloromethane 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 0.045 mL / min. The distance between the injection head and the receiving electrode was fixed at 15 cm, and the spinning voltage was 18 kV. The membrane material PET / PDA / CM was obtained by vacuum drying at 50 °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 Janus membrane achieved separation efficiencies of 88%, 88%, 83%, and 81% for petroleum ether (T / W), n-hexane (X / W), n-heptane (P / W), and chloroform (L / W) in water, respectively.

[0049] Janus membranes achieved permeation fluxes of 11070 L / m for T / W, X / W, P / W, and L / W emulsions, respectively. -2 h -1 bar -1 9490L m -2 h -1 bar -1 8630 L m -2 h -1 bar -1 and 8440 L m -2 h -1 bar -1 The separation efficiencies for petroleum ether-in-water (W / T), n-hexane-in-water (W / X), n-heptane-in-water (W / P), and chloroform-in-water (W / L) emulsions were 83%, 84%, 82%, and 80%, respectively.

[0050] The Janus membrane had a permeation flux of 1170 L / m for W / T, W / X, W / P, and W / L emulsions, respectively. -2 h -1 bar -1 1065 Lm -2 h -1 bar -1 1023 L m -2h -1 bar -1 969 L m -2 h -1 bar -1 .

[0051] Example 3

[0052] A method for preparing a Janus cellulose membrane based on waste plastic 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 PET membrane was constructed on the surface of a superhydrophilic PDA / CM using electrospinning technology. The specific steps are as follows: 1.5 g of PET plastic sheet was dissolved in 100 mL of a trifluoroacetic acid / dichloromethane mixed solution (volume ratio 3:7) at 25 °C to form an electrospinning precursor solution. The precursor solution was injected into a 10 mL syringe, and the spinning rate was set to 0.037 mL / min. The distance between the injection head and the receiving electrode was fixed at 20 cm, and the spinning voltage was 17 kV. The membrane material PET / PDA / CM was obtained by vacuum drying at 50 °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] Janus membranes exhibit high separation efficiency for petroleum ether in water (T / W), n-hexane in water (X / W), n-heptane in water (P / W), and chloroform in water (L / W), with separation efficiencies reaching over 98%.

[0058] Janus membranes achieved permeation fluxes of 14770 L / m for T / W, X / W, P / W, and L / W emulsions, respectively. -2 h -1 bar -1 13195L m -2 h -1 bar -1 14950 L m -2 h -1 bar -1 and 11105 L m-2 h -1 bar -1 The separation efficiency for petroleum ether-in-water (W / T), n-hexane-in-water (W / X), n-heptane-in-water (W / P), and chloroform-in-water (W / L) emulsions is as high as 98.7%.

[0059] The Janus membrane had a permeation flux of 1877 L / m for W / T, W / X, W / P, and W / L emulsions, respectively. -2 h -1 bar -1 1590 Lm -2 h -1 bar -1 1719 L m -2 h -1 bar -1 1510 L m -2 h -1 bar -1 .

[0060] Example 4

[0061] A method for preparing a Janus cellulose membrane based on waste plastic includes the following steps:

[0062] a) After soaking the waste qualitative filter paper in 7.5 wt% dilute hydrochloric acid for 18 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 4 g / L DA-HCl solution at pH=8.5 and soaked at 25 ℃ for 8 h. The resulting dopamine modified membrane material PDA / CM was vacuum dried at 50 ℃ for 12 h for later use.

[0064] c) A hydrophobic PET membrane was constructed on the surface of a superhydrophilic PDA / CM using electrospinning technology. The specific steps are as follows: 3 g of PET plastic sheet was dissolved in 100 mL of a 2:8 trifluoroacetic acid / dichloromethane 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 0.066 mL / min. The distance between the injection head and the receiving electrode was fixed at 18 cm, and the spinning voltage was 20 kV. The membrane material PET / PDA / CM was obtained by vacuum drying at 50 °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 Janus membrane achieved separation efficiencies of 94%, 90%, 95%, and 86% for petroleum ether in water (T / W), n-hexane in water (X / W), n-heptane in water (P / W), and chloroform in water (L / W), respectively.

[0067] Janus membranes achieved permeation fluxes of 13170 L / m for T / W, X / W, P / W, and L / W emulsions, respectively. -2 h -1 bar -1 12695L m -2 h -1 bar -1 12550 L m -2 h -1 bar -1 and 9305 L m -2 h -1 bar -1 The separation efficiencies for petroleum ether-in-water (W / T), n-hexane-in-water (W / X), n-heptane-in-water (W / P), and chloroform-in-water (W / L) emulsions were 92%, 90%, 91%, and 88%, respectively.

[0068] The Janus membrane had a permeation flux of 1677 L / m for W / T, W / X, W / P, and W / L emulsions, respectively. -2 h -1 bar -1 1390 Lm -2 h -1 bar -1 1410 L m -2 h -1 bar -1 1310 L m -2 h -1 bar -1 .

[0069] Example 5

[0070] A method for preparing a Janus cellulose membrane based on waste plastic 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 PET membrane was constructed on the surface of a superhydrophilic PDA / CM using electrospinning technology. The specific steps are as follows: 5 g of PET plastic sheet was dissolved in 100 mL of a trifluoroacetic acid / dichloromethane mixed solution (9:1 volume ratio) 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 0.1 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 PET / PDA / CM was obtained by vacuum drying at 50 °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 Janus membrane achieved separation efficiencies of 95%, 93%, 96%, and 88% for petroleum ether in water (T / W), n-hexane in water (X / W), n-heptane in water (P / W), and chloroform in water (L / W), respectively.

[0076] Janus membranes achieved permeation fluxes of 13970 L / m for T / W, X / W, P / W, and L / W emulsions, respectively. -2 h -1 bar -1 12995L m -2 h -1 bar -1 13050 L m -2 h -1 bar -1 and 9395 L m -2 h -1 bar -1 The separation efficiencies for petroleum ether-in-water (W / T), n-hexane-in-water (W / X), n-heptane-in-water (W / P), and chloroform-in-water (W / L) emulsions were 94%, 91%, 92%, and 92%, respectively.

[0077] The Janus membrane had a permeation flux of 1737 L / m for W / T, W / X, W / P, and W / L emulsions, respectively. -2 h -1 bar -1 1410 Lm -2 h -1 bar -1 1450 L m -2 h -1 bar -1 1360 L m -2 h -1 bar -1 .

[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 Janus cellulose membrane based on waste plastic, characterized in that, Includes the following steps: a) After soaking the waste qualitative filter paper in 1-10 wt% dilute hydrochloric acid for 12-36 hours, it is washed multiple times with ethanol and deionized water, and then vacuum dried at 50°C for 4 hours to obtain cellulose membrane CM. b) The fiber membrane CM was suspended and immersed in a 0.5-5 g / L DA-HCl solution at pH 8.5 for 2-48 h at 25 °C. The resulting superhydrophilic dopamine-modified membrane PDA / CM was then vacuum dried at 50 °C for 12 h. c) Electrospin hydrophobic PET onto the surface of a superhydrophilic dopamine-modified PDA / CM membrane, and vacuum dry at 50°C to obtain a Janus cellulose membrane based on waste plastic. The electrospinning, i.e., electrospinning, specifically involves the following steps: dissolving 0.5–5 g of PET plastic sheet in 100 mL of a trifluoroacetic acid / dichloromethane mixed solution with a volume ratio of 1:9–9:1 at 20–50°C to form an electrospinning precursor solution; injecting the precursor solution into a 10 mL syringe, setting the spinning rate to 0.010–0.1 mL / min, fixing the distance between the injection head and the receiving electrode to 12–25 cm, and setting the spinning voltage to 15–25 kV.

2. The method for preparing Janus cellulose membrane based on waste plastic according to claim 1, characterized in that: In step a), the waste qualitative filter paper is soaked in 6wt% dilute hydrochloric acid for 24 hours.

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

4. The method for preparing Janus cellulose membrane based on waste plastic according to claim 1, characterized in that: At 25°C, 1.5g of PET plastic sheet is dissolved in 100 mL of a trifluoroacetic acid / dichloromethane mixed solution with a volume ratio of 3:7 to form an electrospinning precursor solution.

5. The method for preparing Janus cellulose membrane based on waste plastic according to claim 1, characterized in that: The spinning rate was set to 0.037 mL / min, the distance between the injection head and the receiving electrode was fixed at 20 cm, and the spinning voltage was 17 kV.

6. Janus cellulose membrane based on waste plastic prepared by any one of claims 1-5.

7. The Janus cellulose membrane based on waste plastic according to claim 6, characterized in that: The Janus cellulose membrane has asymmetric wetting properties.

8. An application of the Janus cellulose membrane as described in claim 6 or 7, characterized in that: It is applied to emulsion separation.

9. The application of the Janus cellulose membrane according to claim 8, characterized in that: The emulsion includes water-in-oil emulsion and oil-in-water emulsion.

Images