PET efficient continuous degradation process based on membrane method technology

Abstract

The invention discloses an efficient continuous PET (polyethylene terephthalate) degradation process based on a membrane method technology, which comprises the following steps: mixing an immobilized enzyme compound, a PET raw material to be degraded and a glycine buffer solution to form a reaction solution for degradation, then constructing a'continuous reactor 'by using two size screening membranes, performing primary separation by using an ultrafiltration membrane or a microfiltration membrane, and performing secondary separation by using an ultrafiltration membrane or a microfiltration membrane. A nanofiltration membrane or a reverse osmosis membrane is adopted for secondary separation of the degradation product, automatic separation of the degradation product and a reaction system and automatic purification of the degradation product are achieved, and then the enzymatic degradation efficiency and the product recovery efficiency are improved. Through the construction of the continuous reactor, the automatic PET degradation is realized, so that the costs in the aspects of labor, time, economy and the like are remarkably saved. The undegraded PET and a small amount of exfoliative enzyme can be circulated back to the reaction kettle after being intercepted by the size screening membrane, and the process not only can promote full contact between the undegraded PET and the hydrolase, but also can reduce the loss of the enzyme in the degradation process.

Description

Technical Field

[0001] The invention belongs to the technical field of PET degradation and recovery, and specifically relates to a PET efficient and continuous degradation process based on membrane technology. Background Art

[0002] Polyethylene terephthalate (PET) is a common thermoplastic formed by the polymerization of terephthalic acid and ethylene glycol. Due to its excellent mechanical and thermal properties, it is widely used in textile fiber films, plastic bottles and other fields, and its annual consumption accounts for 18% of the total plastic consumption. PET plastic cannot be degraded under natural environmental conditions and is easy to accumulate in the environment, making it one of the main sources of "plastic pollution". Therefore, it is necessary to develop efficient PET waste treatment and upgrading transformation paths to solve the pollution problem of PET plastics and promote the resource utilization of waste.

[0003] Bioenzyme degradation and recycling is a PET waste treatment method with broad application prospects. This method uses PET hydrolases selected from natural microorganisms or obtained by site-directed mutation to contact the polymer chains in PET plastics under the drive of water, and hydrolyzes the macromolecular PET into small molecular products such as mono(2-hydroxyethyl)terephthalate (MHET), terephthalic acid (TPA), and ethylene glycol (EG) by breaking the ester bond. These products can be recycled and reused as chemical raw materials. Therefore, there is no pollution in the degradation process, the recovery rate is high, the recycled plastics are of high quality and the cost is low.

[0004] The current degradation process is intermittent and requires regular replacement of the reaction liquid in the reactor. This is due to: 1. Product inhibition: As the product is continuously generated, the reaction product will combine with the enzyme, thereby reducing the activity of the enzyme, and the rate of enzyme degradation will also be significantly reduced; 2. Changes in the degradation environment: The activity of PET degradation enzyme is highest in an alkaline environment of pH 9.0. As the reaction proceeds, acidic products are continuously generated, and the alkaline environment is destroyed, resulting in a decrease in enzyme activity, thereby inhibiting the enzyme degradation process.

[0005] Therefore, it is necessary to develop a continuous and automated enzymatic degradation process to achieve efficient enzymatic degradation of PET waste. Summary of the invention

[0006] The object of the present invention is to achieve high efficiency and continuity of PET degradation process by optimizing degradation process by membrane method. This process mode is different from the traditional intermittent bio-enzyme degradation process. It uses two size screening membranes to construct a "continuous reactor", realizes automatic separation and purification of degradation products and reaction system, and thus improves enzyme degradation and product recovery efficiency. At the same time, the "enzyme fixation" technology is used to reduce enzyme loss and enhance enzyme activity. Finally, automated PET enzyme degradation is achieved, which greatly saves labor, time and economic costs.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] In a first aspect, the present invention provides a PET efficient continuous degradation process based on membrane technology, comprising the following steps:

[0009] (a) immobilizing PET biodegradation enzyme in amino resin to form an immobilized enzyme complex;

[0010] (b) putting the immobilized enzyme complex, the PET raw material to be degraded and the glycine buffer into a reaction tank to form a reaction solution, and performing a degradation reaction at a constant temperature of 50 to 60° C.;

[0011] (c) The reaction solution is transported to a flat plate filter through a circulation pump, using an effective area of ​​4 × 4 cm 2 Up to 10×10cm 2 The ultrafiltration membrane or microfiltration membrane intercepts the undegraded PET raw material and the detached PET biodegradation enzyme, and returns the intercepted material to the reaction tank through the circulation pump; at the same time, the filtrate containing the degradation product is collected into the filtrate tank;

[0012] (d) The filtrate is transported to the RO (reverse osmosis) module through a high-pressure pump, using an effective area of ​​2×2 cm 2 Up to 6×6cm 2 The degradation products are separated by nanofiltration membrane or reverse osmosis membrane.

[0013] (e) After the reaction is completed, the degradation products are recovered.

[0014] Preferably, the degradation products are terephthalic acid (TPA) and bis(2-hydroxyethyl) terephthalate (MHET).

[0015] Preferably, the concentration of the glycine buffer is 50-55 mM, and the pH value is 8.8-9.2.

[0016] Preferably, the PET biodegradation enzyme is FAST-PETase-N212A / N277A enzyme.

[0017] Preferably, since the temperature of the filtrate should not be too high when it is pressed into the reverse osmosis membrane by the high-pressure pump, a refrigerator is used to cool the filtrate containing the degradation products when it is collected into the filtrate tank.

[0018] In the technical solution of the present invention, the material of the ultrafiltration membrane or microfiltration membrane is polyethersulfone (PES), polysulfone (PS), cellulose acetate (CA), polypropylene (PP), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), etc. The molecular weight cutoff of the ultrafiltration membrane is between 1000Da and 500000Da, and the molecular weight cutoff of the microfiltration membrane is between 0.1 and 1μm. Preferably, an ultrafiltration membrane is used, specifically with a molecular weight cutoff of 10kDa, and a water flux of 20mL / (cm2 at a positive pressure of 0.5MPa. 2 h) PES ultrafiltration membrane;

[0019] In the technical solution of the present invention, the material of the nanofiltration membrane is cellulose acetate (CA), polysulfone (PS), sulfonated polysulfone (SPS), polyethersulfone (PES), polypropylene (PP), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTEE), polyamide (PA), etc., and the interception molecular weight is between 100Da and 2000Da. The material of the reverse osmosis membrane is cellulose acetate (CA), polyethersulfone (PES), polyamide (PA), etc., and the interception molecular weight is between 100Da and 200Da. Preferably, a reverse osmosis membrane is used, specifically with a molecular weight interception of 100Da, and a water flux of 5mL / (cm 2 h) PA reverse osmosis membrane.

[0020] In a second aspect, the present invention provides a continuous reactor for realizing the above-mentioned continuous degradation process, comprising a degradation module, a first separation module and a second separation module connected in sequence;

[0021] Wherein, the degradation module comprises a reaction tank, a heater and a circulation pump, the heater heats the reaction tank, the reaction tank comprises a feeding port and a discharging port, and the discharging port of the reaction tank is connected to the circulation pump;

[0022] The first separation module includes a flat filter, a filtered liquid tank, a refrigerator and a high-pressure pump. The flat filter is provided with an ultrafiltration membrane or a microfiltration membrane for intercepting undegraded PET raw materials and detached PET biodegradation enzymes, and returning them to the reaction tank through a circulation pump, while collecting the filtered liquid containing degradation products to the filtered liquid tank; the refrigerator is used to reduce the temperature in the filtered liquid tank; the discharge port of the filtered liquid tank is connected to the high-pressure pump;

[0023] The second separation module includes an RO component, a permeate tank and a transfer pump. The RO component is provided with a nanofiltration membrane or a reverse osmosis membrane; the feed port of the RO component is connected to the high-pressure pump, and the discharge port is connected to the permeate tank; the transfer pump is used to transfer the liquid in the permeate tank back to the reaction tank for recycling.

[0024] The beneficial effects of the present invention are at least:

[0025] The present invention constructs a continuous process flow, innovatively introduces two size screening membranes to construct a "continuous reactor", and adopts "enzyme fixation" technology to optimize the performance of PET hydrolase and reduce the loss of enzyme during degradation. During the reaction process, undegraded PET and a small amount of enzyme falling off from the modified amino resin powder will be intercepted by the ultrafiltration membrane, and these intercepted substances will be recirculated to the reactor to ensure that the undegraded PET can react with the hydrolase again. This circulation mechanism not only strengthens the contact opportunity between the undegraded PET and the hydrolase, so that they can interact more fully, but also effectively reduces the unnecessary loss of the enzyme during the degradation process, thereby improving the efficiency and resource utilization of the entire reaction system. In addition, the reverse osmosis membrane introduced at the rear end of the ultrafiltration membrane can realize the automatic purification of the degradation product. This automated process can not only significantly improve the enzyme degradation efficiency and product recovery efficiency, but also significantly save the costs of manpower, time and economy, etc., and has good application prospects.

[0026] The present invention uses a membrane optimization strategy to simultaneously achieve product separation during the degradation process, thereby eliminating the inhibitory effect of product accumulation in the reactor on the activity of the biological enzyme and the forward progress of the degradation reaction in the traditional degradation process. It is simple and easy to implement and has high controllability and repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Optimization process flow chart for PET degradable film method.

[0028] Figure 2 It is a comparison chart of the degradation cycle between the comparative example and Examples 1-6.

[0029] Figure 3 It is a comparison chart of degradation cost between comparative example and examples 1-6. DETAILED DESCRIPTION

[0030] Some typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have many variations in different schemes without departing from the scope of the present invention. And the descriptions and illustrations therein are essentially illustrative, not limiting, of the present invention.

[0031] In the embodiment of the present invention, the PET product to be recycled is produced by Goodfellow Company of the United Kingdom and has a thickness of 0.25 mm. The film parameters used are detailed in Table 1.

[0032] Table 1

[0033] Material Manufacturer model Membrane pore size Molecular weight cut-off PES ultrafiltration membrane China LABSELECT ufc-150-010-pes 0.1μm 10kDa PA reverse osmosis membrane Toray Industries, Inc. TMG20-400C 0.1nm 100Da PVDF microfiltration membrane Mitsubishi Chemical Corporation 50E0025SA 0.4μm 1000kDa PA Nanofiltration Membrane DowFilmtec NF90-2540 1nm 200Da CA ultrafiltration membrane Whatman Company, UK OE66 0.2μm 10kDa PVDF Nanofiltration Membrane China Suez Company GEHL2540FM 1nm 200Da PP ultrafiltration membrane Liuzhou Yuanyang Environmental Protection Technology Co., Ltd. UF-2880 0.01μm 8kDa PS Nanofiltration Membrane DowDuPont NF90-4040 1nm 200Da PAN ultrafiltration membrane Shanghai Huamo Industrial Co., Ltd. UF4021 0.01μm 10kDa PP nanofiltration membrane Shihan Energy Saving and Environmental Protection Technology Co., Ltd. NE4040-90 1nm 100Da

[0034] like Figure 1As shown, the present invention provides a PET efficient continuous degradation process based on membrane technology. First, the PET biodegradation enzyme is fixed in the resin material, and the resin material after enzyme fixation and the PET raw material to be degraded are put into a reactor filled with 50-55mM glycine buffer solution with pH 8.8-9.2. The total volume of the mixture is 800mL. During the degradation process, the continuous reactor device is kept at a constant temperature of 50-60°C. The reaction liquid will be partially transported to the flat filter under the action of the circulation pump. The flat filter adopts an effective area of ​​4×4cm 2 ~10×10cm 2 The ultrafiltration membrane or microfiltration membrane is used to intercept the undegraded PET raw materials. The ultrafiltration membrane with a smaller pore size can even intercept the detached biodegradation enzymes. The intercepted substances can be transported back to the reactor with a small amount of reaction liquid through the circulation pump to continue the reaction, while the small molecule products and a large amount of filtrate that pass through the flat filter can be temporarily stored in the filtrate tank. Among them, the material of the ultrafiltration membrane or microfiltration membrane is selected from one of polyether sulfone, polysulfone, cellulose acetate, polypropylene, polyvinylidene fluoride, and polyacrylonitrile. The interception molecular weight of the ultrafiltration membrane is between 1000Da and 500000Da, and the interception molecular weight of the microfiltration membrane is between 0.1 and 1μm. Then, these filtrates containing small molecule products are transported to the RO component through a high-pressure pump. The RO component adopts an effective area of ​​2×2cm 2 ~6×6cm 2 Nanofiltration membrane or reverse osmosis membrane, to achieve secondary separation of small molecule products. Wherein, the material of the nanofiltration membrane is selected from one of cellulose acetate, polysulfone, sulfonated polysulfone, polyethersulfone, polypropylene, polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, polyamide, and the interception molecular weight is between 100Da and 2000Da; the material of the reverse osmosis membrane is selected from one of cellulose acetate, polyethersulfone, polyamide, and the interception molecular weight is between 100Da and 200Da. After the degradation of PET is completed, the degradation product terephthalic acid (TPA, molecular weight is 168.2Da) and the intermediate product bis(2-hydroxyethyl) terephthalate (MHET, molecular weight is 191.1Da) can be directly recovered.

[0035] The present invention is further described below in conjunction with specific embodiments.

[0036] Example 1

[0037] In the process constructed, a 10×10 cm 2 The water flux under 0.5MPa positive pressure is 20mL / (cm 2 h) PES ultrafiltration membrane, 4×4cm 2 The water flux under 0.3MPa positive pressure is 5mL / (cm 2·h) of PA reverse osmosis membrane. The type of enzyme immobilized in the enzyme immobilized porous membrane is FAST-PETase-N212A / N277A enzyme. Take 10mg PET and grind it, mix it thoroughly with water, additives, etc., and put it into the built continuous reactor. The pH in the reactor is maintained at about 9.0, the degradation temperature is 50℃, and the circulation pump pressure is 0.5MPa. Every 1h, high performance liquid chromatography (HPLC) is used to determine and analyze whether there is still product flowing out of the flat filter, and the degradation cycle is calculated. The analytical column is InertSustain C18column (4.6×250mm, 5μm), the mobile phase is methanol / phosphate (20mM, pH 2.5), the flow rate is 1mL / min, the detection wavelength is 254nm, the elution condition is 0-15min, and the methanol linear gradient is 35%-70%.

[0038] Example 2

[0039] In the process constructed, a 4×4cm flat filter is used 2 The water flux under 0.5MPa positive pressure is 80mL / (cm 2 h) PVDF microfiltration membrane, 4×4cm 2 The water flux under 0.3MPa positive pressure is 5mL / (cm 2 ·h) of PA reverse osmosis membrane. The type of enzyme immobilized in the enzyme immobilized porous membrane is FAST-PETase-N212A / N277A enzyme. Take 10mg PET and grind it, mix it thoroughly with water, additives, etc., and put it into the built continuous reactor. The pH in the reactor is maintained at about 9.0, the degradation temperature is 50℃, and the circulation pump pressure is 0.5MPa. Every 1h, high performance liquid chromatography (HPLC) is used to determine and analyze whether there is still product flowing out of the flat filter, and the degradation cycle is calculated. The analytical column is InertSustain C18column (4.6×250mm, 5μm), the mobile phase is methanol / phosphate (20mM, pH 2.5), the flow rate is 1mL / min, the detection wavelength is 254nm, the elution condition is 0-15min, and the methanol linear gradient is 35%-70%.

[0040] Example 3

[0041] In the process constructed, a 4×4cm flat filter is used 2 The water flux under 0.5MPa positive pressure is 20mL / (cm 2 h) PES ultrafiltration membrane, 2×2cm 2 The water flux under 0.5MPa positive pressure is 10mL / (cm 2·h) PA nanofiltration membrane. The enzyme immobilized in the enzyme immobilization porous membrane is FAST-PETase-N212A / N277A enzyme. 10 mg of PET was ground and mixed with water, additives, etc., and then put into the built continuous reactor. The pH in the reactor was maintained at about 9.0, the degradation temperature was 50°C, and the circulating pump pressure was 0.5 MPa. Every 1 hour, high performance liquid chromatography (HPLC) was used to determine and analyze whether there was still product flowing out of the flat filter, and the degradation cycle was calculated. The analytical column was InertSustain C18column (4.6×250mm, 5μm), the mobile phase was methanol / phosphate (20mM, pH 2.5), the flow rate was 1mL / min, the detection wavelength was 254nm, the elution conditions were 0-15min, and the methanol linear gradient was 35%-70%.

[0042] Example 4

[0043] In the process constructed, the flat filter uses 8×8cm 2 The water flux under 0.5MPa positive pressure is 20mL / (cm 2 h) CA ultrafiltration membrane, 6×6cm in RO module 2 The water flux under 0.3MPa positive pressure is 5mL / (cm 2 ·h) of PVDF nanofiltration membrane. The enzyme type immobilized in the enzyme immobilization porous membrane is FAST-PETase-N212A / N277A enzyme. Take 10mg PET and grind it, mix it with water, additives, etc., and put it into the built continuous reactor. The pH in the reactor is maintained at about 9.0, the degradation temperature is 50℃, and the circulation pump pressure is 0.5MPa. Every 1h, high performance liquid chromatography (HPLC) is used to determine and analyze whether there is still product flowing out of the flat filter, and the degradation cycle is calculated. The analytical column is InertSustain C18column (4.6×250mm, 5μm), the mobile phase is methanol / phosphate (20mM, pH 2.5), the flow rate is 1mL / min, the detection wavelength is 254nm, the elution condition is 0-15min, and the methanol linear gradient is 35%-70%.

[0044] Example 5

[0045] In the process constructed, a 4×4cm flat filter is used 2 The water flux under 0.5MPa positive pressure is 20mL / (cm 2 h) PP ultrafiltration membrane, 6×6cm in RO module 2 The water flux under 0.3MPa positive pressure is 5mL / (cm 2·h) of PS nanofiltration membrane. The enzyme immobilized in the enzyme immobilization porous membrane is FAST-PETase-N212A / N277A enzyme. 10 mg of PET was ground and mixed with water, additives, etc., and then put into the built continuous reactor. The pH in the reactor was maintained at about 9.0, the degradation temperature was 50°C, and the circulating pump pressure was 0.5 MPa. Every 1 hour, high performance liquid chromatography (HPLC) was used to determine and analyze whether there was still product flowing out of the flat filter, and the degradation cycle was calculated. The analytical column was InertSustain C18column (4.6×250mm, 5μm), the mobile phase was methanol / phosphate (20mM, pH 2.5), the flow rate was 1mL / min, the detection wavelength was 254nm, the elution conditions were 0-15min, and the methanol linear gradient was 35%-70%.

[0046] Example 6

[0047] In the process constructed, a 10×10 cm 2 The water flux under 0.5MPa positive pressure is 20mL / (cm 2 h) PAN ultrafiltration membrane, 6×6cm 2 The water flux under 0.3MPa positive pressure is 5mL / (cm 2 ·h) of PP nanofiltration membrane. The type of enzyme immobilized in the enzyme immobilized porous membrane is FAST-PETase-N212A / N277A enzyme. Take 10mg PET and grind it, mix it with water, additives, etc., and put it into the built continuous reactor. The pH in the reactor is maintained at about 9.0, the degradation temperature is 50℃, and the circulation pump pressure is 0.5MPa. Every 1h, high performance liquid chromatography (HPLC) is used to determine and analyze whether there is still product flowing out of the flat filter, and the degradation cycle is calculated. The analytical column is InertSustain C18column (4.6×250mm, 5μm), the mobile phase is methanol / phosphate (20mM, pH 2.5), the flow rate is 1mL / min, the detection wavelength is 254nm, the elution condition is 0-15min, and the methanol linear gradient is 35%-70%.

[0048] Comparative Example

[0049] Take 10mg PET and grind it, mix it with water, additives, etc., and put it into a closed reactor. Add 50nL FAST-PETase-N212A / N277A enzyme (5μg / mL) to form a 1mL mixture, and place it in a 50mM glycine, pH 9.0 buffer for degradation test, and the degradation temperature is 50℃. Every 6h, high performance liquid chromatography (HPLC) is used to determine and analyze whether the product in the reaction solution is still increasing, and the degradation cycle is calculated. The analytical column is InertSustain C18column (4.6×250mm, 5μm), the mobile phase is methanol / phosphate (20mM, pH 2.5), the flow rate is 1mL / min, the detection wavelength is 254nm, the elution condition is 0-15min, and the methanol linear gradient is 35%-70%.

[0050] By comparing various data of Examples 1-6 with the comparative examples during the degradation process, such as degradation cycle, degradation cost (such as Figure 2-3 As shown in the figure, it can be clearly seen that the method of the present invention has a significant effect in improving the efficiency of bio-enzyme degradation and reducing the cost of enzyme degradation. Compared with the PET products degraded in a traditional single reactor (comparative example), the PET products degraded in the continuous process (Examples 1-6) have a shorter degradation cycle ( Figure 2 ) and lower degradation costs ( Figure 3 ), this is because the continuous process designed by the present invention adopts membrane size screening technology to separate reactants and products, promote the reaction to shift to the right, accelerate the reaction process, and improve the utilization rate of enzymes through enzyme immobilization technology, increase the contact area between enzymes and substrates, and further improve the degradation efficiency. Therefore, the present invention provides a more advantageous solution for the recycling of PET products.

[0051] In summary, the present invention improves the traditional enzyme degradation process, transforms the closed process into a cyclic continuous process, and uses enzyme immobilization technology and membrane size screening technology to further improve the efficiency of enzyme degradation. The degradation cycle is shortened from the original 24h to 5-8h, and the degradation cost is reduced from the original nearly 600 yuan to about 50-100 yuan, solving the pain point of high cost of biological enzyme degradation, and this process can further guide the research on the process mode of enzyme degradation of PET.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-efficiency continuous degradation process for PET based on membrane technology, characterized in that: The following steps are involved: (a) immobilizing PET biodegradation enzyme in amino resin to form an immobilized enzyme complex; (b) putting the immobilized enzyme complex, the PET raw material to be degraded and the glycine buffer into a reaction tank to form a reaction solution, and performing a degradation reaction at a constant temperature of 50 to 60° C.; (c) The reaction solution is transported to a flat plate filter through a circulation pump, using an effective area of ​​4 × 4 cm 2 Up to 10×10cm 2 The ultrafiltration membrane or microfiltration membrane intercepts the undegraded PET raw material and the detached PET biodegradation enzyme, and returns the intercepted material to the reaction tank through the circulation pump; at the same time, the filtrate containing the degradation product is collected into the filtrate tank; (d) The filtrate is transported to the RO reverse osmosis module through a high-pressure pump, using an effective area of ​​2×2 cm 2 Up to 6×6cm 2 The degradation products are separated by nanofiltration membrane or reverse osmosis membrane. (e) After the reaction is completed, the degradation products are recovered.

2. The PET efficient continuous degradation process based on membrane technology according to claim 1 is characterized in that: The degradation products are terephthalic acid and bis(2-hydroxyethyl)terephthalate.

3. The PET efficient continuous degradation process based on membrane technology according to claim 1 is characterized in that: The concentration of the glycine buffer is 50-55 mM, and the pH value is 8.8-9.

2.

4. The PET efficient continuous degradation process based on membrane technology according to claim 1 is characterized in that: The PET biodegradation enzyme is FAST-PETase-N212A / N277A enzyme.

5. The PET efficient continuous degradation process based on membrane technology according to claim 1 is characterized in that: The material of the ultrafiltration membrane or microfiltration membrane is selected from one of polyethersulfone, polysulfone, cellulose acetate, polypropylene, polyvinylidene fluoride, and polyacrylonitrile. The interception molecular weight of the ultrafiltration membrane is between 1000Da and 500000Da, and the interception molecular weight of the microfiltration membrane is between 0.1 and 1μm.

6. The efficient continuous degradation process of PET based on membrane technology according to claim 5, characterized in that: Step (c) uses a molecular weight cutoff of 10 kDa and a water flux of 20 mL / (cm 2 h) polyethersulfone ultrafiltration membrane.

7. The efficient and continuous degradation process of PET based on membrane technology according to claim 1 is characterized in that: The material of the nanofiltration membrane is selected from one of cellulose acetate, polysulfone, sulfonated polysulfone, polyethersulfone, polypropylene, polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, and polyamide, and the interception molecular weight is between 100Da and 2000Da; the material of the reverse osmosis membrane is selected from one of cellulose acetate, polyethersulfone, and polyamide, and the interception molecular weight is between 100Da and 200Da.

8. The high-efficiency continuous degradation process of PET based on membrane technology according to claim 7 is characterized in that: Step (d) uses a molecular weight cutoff of 100Da and a water flux of 5mL / (cm 2 h) polyamide reverse osmosis membrane.

9. The PET efficient continuous degradation process based on membrane technology according to claim 1, characterized in that: When the filtrate containing the degradation product is collected into the filtrate tank in step (c), a refrigerator is used to cool the filtrate.

10. A continuous reactor for implementing the continuous degradation process according to any one of claims 1 to 9, comprising a degradation module, a first separation module and a second separation module connected in sequence; in, The degradation module comprises a reaction tank, a heater and a circulation pump, wherein the heater heats the reaction tank, the reaction tank comprises a feeding port and a discharging port, and the discharging port of the reaction tank is connected to the circulation pump; The first separation module includes a flat filter, a filtrate tank, a refrigerator and a high-pressure pump. The flat filter is provided with an ultrafiltration membrane or a microfiltration membrane for intercepting undegraded PET raw materials and detached PET biodegradation enzymes, and returning them to the reaction tank through a circulation pump, while collecting the filtrate containing degradation products to the filtrate tank; the refrigerator is used to reduce the temperature of the filtrate; the outlet of the filtrate tank is connected to the high-pressure pump; The second separation module includes an RO component, a permeate tank and a transfer pump. The RO component is provided with a nanofiltration membrane or a reverse osmosis membrane; the feed port of the RO component is connected to the high-pressure pump, and the discharge port is connected to the permeate tank; the transfer pump is used to transfer the liquid in the permeate tank back to the reaction tank.

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