Method for improving enzymolysis efficiency of polyester through pretreatment of alkaline eutectic solvent

Abstract

The invention belongs to the technical field of degradation of waste textiles, and relates to a method for improving enzymolysis efficiency of polyester through pretreatment of an alkaline eutectic solvent, which comprises the following steps: mixing a hydrogen bond donor and a hydrogen bond acceptor, heating and stirring until the mixture is clear and transparent to obtain the eutectic solvent; the preparation method comprises the following steps: soaking terylene in a deep eutectic solvent, separating out terylene, and washing with ethanol and deionized water until the pH is neutral, so as to obtain pretreated terylene; cutinase is dissolved in a Tris-HCl buffer solution to obtain an enzymolysis solution, pretreated polyester is immersed for a reaction, and then inactivation is performed. The deep-eutectic solvent is adopted for promoting cutinase to conduct enzymolysis on the polyester, the deep-eutectic solvent has the advantages of being simple in preparation method, low in cost, biodegradable, recyclable and non-toxic, the crystallization degree of the polyester is reduced through the CHCl / EA deep-eutectic solvent, then enzymolysis is conducted, and the total product release amount of enzyme hydrolysis is increased by 5 times.

Description

Technical Field

[0001] The invention relates to a method for improving the enzymatic hydrolysis efficiency of polyester by utilizing alkaline deep eutectic solvent pretreatment, and belongs to the technical field of waste polyester degradation. Background Art

[0002] Polyester (PET) is a linear macromolecule formed by the ester polymerization of ethylene glycol and terephthalic acid. It is primarily used in the plastic packaging and textile industries. However, many countries lack effective waste management, and recycling and reuse of waste PET is inadequate. PET is difficult to degrade naturally, and much of this waste accumulates in the environment, becoming a significant contributor to the global plastic pollution problem. Therefore, addressing PET contamination in the environment is urgent.

[0003] The cutinase degradation method of polyester has mild reaction conditions, does not require a large amount of energy to maintain a high-temperature reaction environment, does not require strong acids or alkalis, and has low requirements for the high-temperature resistance and corrosion resistance of the equipment. It has the advantages of being green and safe. However, the molecules in the crystalline region of polyester are arranged tightly and orderly, the intermolecular forces are strong, and the chemical bonds are wrapped inside and difficult to attack, making it difficult for degradation enzymes or chemical reagents to access the molecular chains, thereby hindering the degradation reaction. The molecular chains in the amorphous region are relatively loosely arranged, with a higher free volume and molecular chain activity, providing more accessible sites for degradation agents or enzymes. When the degree of crystallinity decreases, it means that the proportion of the amorphous region increases, more molecular chains are exposed to the external environment, and are more likely to react with degradation agents, thereby promoting the degradation process.

[0004] Methods for reducing polyester crystallinity include heat treatment, alkali treatment, electron beam irradiation, and low-temperature plasma treatment. However, these methods have harsh reaction conditions and require high equipment. A polyester pretreatment method with mild reaction conditions, environmental friendliness, and low cost is needed to reduce polyester crystallinity and promote cutinase degradation of polyester. Summary of the Invention

[0005]

Technical Issues

[0006] Polyester has a high degree of crystallinity. When cutinase is used to hydrolyze polyester, the enzyme has poor accessibility to the hydrophobic surface, resulting in poor hydrolysis. A polyester pretreatment method with mild reaction conditions, environmental friendliness, and low cost is needed to promote the degradation of polyester by cutinase.

[0007]

Technical solution

[0008] Deep eutectic solvents (DES) are considered a novel solvent that can replace traditional pretreatment solvents, offering advantages such as low price, environmental friendliness, good thermal stability, and recyclability. DES typically consists of hydrogen bond donors and hydrogen bond acceptors. The present invention utilizes alkaline DES pretreatment to disrupt the crystalline regions of polyester, significantly improving the enzymatic hydrolysis of polyester by reducing its crystallinity and increasing its specific surface area.

[0009] A method for improving the enzymatic hydrolysis efficiency of polyester cutinase by pretreatment with an alkaline deep eutectic solvent comprises the following steps:

[0010] (1) mixing a hydrogen bond donor and a hydrogen bond acceptor, heating and stirring until clear and transparent to obtain a deep eutectic solvent;

[0011] (2) soaking polyester with a low eutectic solvent, separating the polyester, and washing with ethanol and deionized water until the pH is neutral to obtain pretreated polyester;

[0012] (3) Dissolve cutinase in Tris-HCl buffer to obtain an enzymatic solution, immerse the pretreated polyester in the reaction, and then inactivate it.

[0013] In one embodiment, in step (1), the hydrogen bond acceptor is choline chloride; and the hydrogen bond donor is one or more of acetic acid, formic acid, lactic acid, glycerol, ethylene glycol, urea, acetamide, monoethanolamine, and triethanolamine.

[0014] In one embodiment, in step (1), the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1-10.

[0015] In one embodiment, in step (1), the temperature of heating and stirring is 80 to 120° C.; and the stirring time is 2 to 8 hours.

[0016] In one embodiment, in step (2), the soaking temperature is 30-100° C., and the soaking time is 15-180 min; preferably, the soaking temperature is 90° C., and the soaking time is 75 min.

[0017] In one embodiment, in step (2), the mass ratio of polyester to the low eutectic solvent is 1:15 to 1:25, preferably 1:20.

[0018] In one embodiment, in step (2), the polyester is separated by centrifugation and / or filtration.

[0019] In one embodiment, in step (2), the crystallinity of the polyester is greater than 30%.

[0020] In one embodiment, in step (3), the cutinase is Humicola insolens cutinase; the enzyme activity is 1000-3000 U / mL; the enzyme concentration of the enzymatic solution is 50-200 U / mL; the enzyme activity is preferably 1800 U / mL; and the enzyme concentration of the enzymatic solution is preferably 100 U / mL.

[0021] In one embodiment, in step (3), the pH of the Tris-HCl buffer is 7.5 to 8.5, and the concentration is 8 to 12 mmol / L; preferably, the pH is 8, and the concentration is 10 mmol / L.

[0022] In one embodiment, in step (3), the mass ratio of the pretreated polyester to the Tris-HCl buffer is 1:40 to 60, preferably 1:50.

[0023] In one embodiment, in step (3), the reaction temperature is 45-55° C., and the reaction time is 60-100 h; preferably, the reaction temperature is 50° C., and the reaction time is 72 h.

[0024] In one embodiment, in step (3), the inactivation is performed by heating in a constant temperature water bath at 95-100° C. for 0.2-1 h.

[0025] The second object of the present invention is to provide application of the above method in the degradation of waste polyester.

[0026] Beneficial effects:

[0027] (1) The present invention uses a low eutectic solvent to promote cutinase enzymatic hydrolysis of polyester. The low eutectic solvent has the advantages of simple preparation method, low cost, biodegradability, recyclability and non-toxicity.

[0028] (2) The present invention reduces the crystallinity of polyester by using CHCl / EA low eutectic solvent and then performs enzymatic hydrolysis, thereby increasing the release amount of the total enzymatic hydrolysis product by 5 times. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 FTIR test results of pretreated PET in Example 1 and Comparative Example 2, (a) Comparative Example 2, (b) Example 1.

[0030] Figure 2 TG test results of pretreated PET in Example 1 and Comparative Example 2, (a) Comparative Example 2, (b) Example 1.

[0031] Figure 3 The DTG test results of the pretreated PET in Example 1 and Comparative Example 2 are shown in Figure 2, (a) Comparative Example 2, and (b) Example 1.

[0032] Figure 4These are the SEM test results of the pretreated PET in Example 1 and Comparative Example 2, (a) Comparative Example 2, (b) Example 1.

[0033] Figure 5 XRD test results of PET pretreated with different DES and Comparative Example 2, (a) Comparative Example 2, (b) Example 1.

[0034] Figure 6 This is the SEM of PET pretreated with NaOH in Comparative Example 1. DETAILED DESCRIPTION

[0035] Material:

[0036] Cutinase is derived from Humicola insolen. The preparation method is based on patent CN 108753671A. The specific fermentation process for producing cutinase includes:

[0037] 1. Seed culture: The E. coli BL21(DE3) / pET-20b(+) / hic strain obtained in CN 108753671A was inoculated into a seed culture medium and cultured on a constant temperature shaker at 37°C and 200 rpm for 8 h.

[0038] 2. Fermentation and enzyme production: The seed liquid was inoculated with 10% of the inoculum into a 3.6 L fermenter for fermentation. The rotation speed in the fermenter was controlled at 300 rpm, the ventilation rate was 1.5 vvm, the dissolved oxygen in the fermentation liquid was maintained at 30%, the temperature was controlled at 37°C, and 25% (v / v) ammonia water was added to control the pH at 7.0. After the initial glycerol was consumed, the dissolved oxygen rose to 80-100%, and the batch fermentation culture was terminated. Feed medium was added in an exponential manner for fed-batch fermentation. When the bacterial cell concentration OD600 reached 75, the temperature was lowered to 30°C and the culture was continued at a flow rate of 0.4-1.2 g·L -1 ·h -1 Lactose solution was added at a constant flow rate for induction, the dissolved oxygen was maintained at 30%, the pH was controlled at about 7.0, the induction was carried out for about 8 hours, and the fermentation supernatant was collected by centrifugation.

[0039] Its nucleotide sequence and amino acid sequence are disclosed in Table 1 of patent CN 113338044 A, and its enzyme activity is 1800U.

[0040] Test method:

[0041] 1. Qualitative and quantitative analysis of hydrolysis products by high performance liquid chromatography (HPLC)

[0042] A Shimadzu LC-20AD series high-performance liquid chromatograph was used, equipped with an Ultimate XB-C18 (4.6 × 250 mm, 5 μm) column and a UV detector. The elution profile used was: mobile phase consisting of 1% glacial acetic acid:methanol (35:65), injection volume of 20 μL, flow rate of 0.5 mL / min, column temperature maintained at approximately 35°C, and detection at 240 nm.

[0043] The hydrolysis products of polyester are terephthalic acid (TPA), mono(hydroxyethyl) phthalate (MHET), and bis-2-(hydroxyethyl) terephthalate (BHET). TPA, MHET, and BHET standard solutions with concentrations of 0.3125 mg / L, 0.625 mg / L, 1.25 mg / L, 2.5 mg / L, 5 mg / L, and 10 mg / L were prepared in methanol. The solutions were tested by HPLC, and a standard curve between peak area (Y-axis) and standard concentration (X-axis) was plotted.

[0044] Y TPA =192085.86098X-9657.73134(R 2 =0.999)

[0045] Y MHET =187432.35366X+35999.75622(R 2 =0.999)

[0046] Y BHET =155570.71557X-35265.91045(R 2 =0.999)

[0047] After the reaction of cutinase with pretreated polyester was completed, the enzyme was inactivated at 100°C for 30 minutes, the reaction system was centrifuged at 10,000 rpm for 5 minutes, the supernatant was filtered through a water-based filter membrane (0.22 μm), and the peak area of ​​the pretreated polyester hydrolyzate at 240 nm was measured by HPLC. The obtained peak area values ​​were substituted into the standard curve to obtain the concentrations C of TPA, MHET, and BHET. TPA 、C MHET 、C BHET Then calculate the total product release amount = C TPA +C MHET +C BHET .

[0048] The qualitative and quantitative analysis of the hydrolyzed product by high performance liquid chromatography (HPLC) is disclosed in patent CN 118326711 A.

[0049] 2. Chemical composition test of polyester pretreatment

[0050] Fourier transform infrared (FTIR) spectrophotometer was used at 400-4000 cm -1 The surface chemical property spectra of pretreated polyester were collected within a wide wavenumber range, and the changes in its chemical bonds and functional groups were analyzed.

[0051] 3. Thermal stability test of polyester pretreatment

[0052] The thermogravimetric analyzer was used in a N2 atmosphere environment. The starting temperature was set at 25°C and the temperature was gradually increased to 800°C at a heating rate of 10.0°C / min to study the pyrolysis characteristics and thermal stability of the pretreated polyester.

[0053] 4. Micromorphology test of polyester pretreatment

[0054] The surface morphology of the pretreated polyester was analyzed using cold field emission scanning electron microscopy (SEM).

[0055] 5. Crystal structure test of polyester pretreatment

[0056] The crystallinity of the pretreated polyester was analyzed under the following conditions: tube voltage 40 kV, tube current 70 mA, scanning speed 4° / min, step width 0.02°, and data analysis was performed within the 2θ range of 5° to 90°.

[0057] Example 1

[0058] A method for improving the enzymatic hydrolysis efficiency of polyester by pretreatment with a deep eutectic solvent, comprising the steps of:

[0059] (1) Choline chloride and monoethanolamine were mixed in a molar ratio of 1:8 and magnetically stirred at 80°C until a transparent and uniform solution was formed to obtain a deep eutectic solvent CHCl / EA;

[0060] (2) soaking polyester with CHCl / EA obtained in step (1) at 90°C for 75 minutes, wherein the mass ratio of polyester to the low eutectic solvent is 1:20, separating the polyester, and washing with ethanol and deionized water until the pH is neutral to obtain pretreated polyester;

[0061] (3) The pretreated polyester was immersed in 10 mmol / L Tris-HCl buffer (pH 8) with a mass ratio of polyester to Tris-HCl buffer of 1:50. Humicola insolens cutinase solution was added to make the enzyme concentration 100 U / mL. The reaction was carried out in a constant temperature shaker at 50°C and 150 rpm for 72 h, and then inactivated at 100°C for 30 min. The mixture was washed with ethanol and deionized water.

[0062] Comparative Example 1

[0063] The only difference from Example 1 is that step (1) is omitted and the CHCl / EA in step (2) is replaced by 40 g / L NaOH solution.

[0064] Comparative Example 2

[0065] The only difference from Example 1 is that step (1) is omitted and CHCl / EA in step (2) is replaced by deionized water.

[0066] Comparative Example 3

[0067] The only difference from Example 1 is that the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor in step (1) is changed to 1:2, and monoethanolamine is replaced by acetic acid, formic acid, lactic acid, ethylene glycol, glycerol, acetamide, urea and triethanolamine, or monoethanolamine is replaced by sorbitol and choline chloride is replaced by betaine to obtain choline chloride / acetic acid (CHCl / AA), choline chloride / formic acid (CHCl / FA), choline chloride / lactic acid (CHCl / LA), choline chloride / ethylene glycol (CHCl / EG), choline chloride / glycerol (CHCl / Gly), choline chloride / acetamide (CHCl / AT), choline chloride / urea (CHCl / U) and choline chloride / trolamine (CHCl / T), betaine / sorbitol (B / S); and the soaking time in step (2) is 1 h. Other parameters and conditions are the same as those in Example 1.

[0068] The reaction solutions of the enzymatic hydrolysis of the polyester pretreated products obtained in Example 1 and Comparative Examples 1 to 3 were centrifuged, and the supernatants were tested. The test results are as follows:

[0069] Table 1 Results of the release of enzymatically hydrolyzed polyester pretreatment products obtained in Example 1 and Comparative Examples 1 to 3

[0070]

[0071] As can be seen from Table 1, the pretreatment of polyester with CHCl / EA significantly increased the release of the total hydrolysis product of polyester. Compared with the polyester pretreated with deionized water (Comparative Example 2), the release of the total hydrolysis product increased by 5 times. The results of Comparative Example 3 show that after pretreatment of polyester with different types of DES, the release of the total hydrolysis product of DES is significantly different. Compared with Comparative Example 2, among DES, the enzymatic hydrolysis effect of the acidic CHCl / FA pretreated polyester is reduced. Acidic CHCl / AA and CHCl / LA, neutral CHCl / EG, CHCl / AT and B / S have little effect on the release of the total enzymatic hydrolysis product. Neutral CHCl / Gly and alkaline CHCl / U, CHCl / T and CHCl / EA can significantly improve the enzymatic hydrolysis effect after pretreatment of polyester.

[0072] Figure 1The FTIR spectra of polyester pretreated in Example 1 and Comparative Example 2 are shown in Figure (a) for Comparative Example 2 and Figure (b) for Example 1. As can be seen from the figure, after CHCl / EA treatment, the wavelengths at 1650 and 1550 cm -1 New peaks are generated at the amide band C=O and the amide band NH vibration peaks. The appearance of these characteristic absorption peaks indicates that the carboxylic acid generated by the hydrolysis of the ester bond will react with the amino group to form an amide bond.

[0073] Thermogravimetric analysis test results are as follows Figure 2 As shown, Figure 2 (a) is Comparative Example 2, and (b) is Example 1. Figure 2 It can be seen that the thermogravimetric curves of polyester pretreated with CHCl / EA and HO show significant differences. Compared with water pretreatment, the polyester pretreated with CHCl / EA exhibits lower residual mass after thermal decomposition. CHCl / EA more easily destroys the molecular structure of PET, resulting in more complete decomposition and less residual solids. The polyester treated with the method of the present invention exhibits a greater thermal weight loss.

[0074] Figure 3 The following are DTG plots of polyester pretreated in Example 1 and Comparative Example 2. Based on TG, changes in thermal properties after pretreatment were further analyzed. Polyester pretreated with CHCl / EA produces PET oligomers. Consequently, there are two thermal weight loss stages at 311.79°C and 438.51°C. However, the polyester pretreated in Comparative Example 2 does not produce oligomers, resulting in only one weight loss stage.

[0075] Figure 4 Figure 1 shows SEM images of the pretreated polyester fibers in Example 1 and Comparative Example 2, with Figure (a) showing Comparative Example 2 and Figure (b) showing Example 1. The surface of the polyester fiber pretreated with H2O in Figure (a) is smooth, while the surface morphology of the polyester fiber in Figure (b) is significantly damaged. This is likely due to the CHCl / EA attacking the polyester ester bonds, destroying the polyester's macromolecular structure and gradually disintegrating the polyester fiber structure.

[0076] Figure 5The XRD patterns of the pretreated polyester in Example 1 and Comparative Example 2 are shown in Figures 1 and 2, (a) is Comparative Example 2, and (b) is Example 1. PET has sharp diffraction peaks at 17.6°, 22.7°, and 25.6°, which are three typical crystal planes (010), (110), and (100), respectively. The crystallinity of the pretreated polyester in Comparative Example 2 is 47.20%. After treatment with CHCl / EA, the positions of the three diffraction peaks did not change significantly, but the intensities of the crystalline phase peaks all decreased, the peak shape became wider, and the crystallinity decreased by 4.44%. In addition, under the same process conditions, the crystallinity of the polyester pretreated with CHCl / FA, CHCl / EG, and NaOH increased by 2.65%, 1.55%, and 1.19%, respectively. Since the pretreatment with CHCl / FA and CHCl / EG failed to significantly reduce the crystallinity of polyester, the enzymatic hydrolysis effect of cutinase on the polyester pretreated with CHCl / FA or CHCl / EG was poor, and the total enzymatic product release was close to or worse than that of the water-pretreated polyester (Comparative Example 2). NaOH first destroys the amorphous regions of PET fibers, generating a large number of oligomers, which leads to an increase in the crystallinity of NaOH-pretreated polyester. Oligomers are easily enzymatically hydrolyzed, so after NaOH pretreatment, the total amount of enzymatic hydrolysis products released by cutinase in polyester increases. CHCl / EA has a higher degree of reduction in crystallinity. Acidic and neutral DES cannot effectively reduce the crystallinity of polyester, but often require higher reaction temperatures and reaction times. Alkaline DES can effectively reduce the crystallinity of polyester and can effectively improve the enzymatic hydrolysis of polyester after alkaline DES pretreatment.

[0077] Figure 6 This is a SEM image of PET treated with NaOH in Comparative Example 1. Etching and voids appear on the polyester surface. NaOH has an etching effect on the polyester surface. However, NaOH's etching effect on polyester fibers is far less pronounced than that of CHCl / EA.

[0078] Comparative Example 4

[0079] The only difference from Example 1 is that step (1) is omitted and the CHCl / EA in step (2) is replaced by choline chloride solution and monoethanolamine solution.

[0080] The total product release of the enzymatic pretreated polyester is shown in Table 2:

[0081] Table 2 Total product release of Comparative Example 4 and Example 1

[0082] PET Choline chloride Monoethanolamine CHCl / EA Total product release (mg / L) 76.08 184.92 297.99

[0083] Example 2

[0084] The only difference from Example 1 is that the molar ratio of the CHCl / EA components in step (1) of Example 1 is adjusted to 1:1, 1:2, 1:4, 1:6, 1:8, and 1:10, respectively, and the soaking pretreatment time in step (2) is 1 h.

[0085] The total product release of the enzymatic pretreated polyester is shown in Table 3:

[0086] Table 3 Effect of hydrogen bond donor and acceptor molar ratio on total product release

[0087] molar ratio 1:1 1:2 1:4 1:6 1:8 1:10 Total product release (mg / L) 108.15 129.37 177.40 195.35 226.22 208.47

[0088] As shown in Table 3, with the increase of monoethanolamine components, the release of the total enzymatic hydrolysis product showed a trend of first increasing and then decreasing.

[0089] Example 3

[0090] The only difference from Example 1 is that the soaking pretreatment temperature in step (2) of Example 1 is adjusted to 20°C, 40°C, 60°C, 80°C, 90°C and 100°C, and the soaking pretreatment time in step (2) is 1 hour.

[0091] The total product release of the enzymatic pretreated polyester is shown in Table 4:

[0092] Table 4 Effect of pretreatment temperature on total product release

[0093] Temperature (℃) 20 40 60 80 90 100 Total product release (mg / L) 86.98 103.83 155.85 196.83 227.33 202.19

[0094] When the temperature rises from 20°C to 90°C, the total hydrolysis product release of the polyester pretreated material increases from 86.98 mg / L to 227.33 mg / L. However, at higher temperatures, the total hydrolysis product release of the pretreated polyester decreases. This is because at higher temperatures, the hydrogen bond network of CHCl / EA weakens, destroying the stability of DES, resulting in a poor pretreatment effect and a decrease in enzymatic hydrolysis products. On the other hand, as the temperature rises, molecular thermal motion increases, promoting the interaction between CHCl / EA and polyester. However, excessively high temperatures may lead to excessive pretreatment of the polyester, resulting in fewer enzyme action sites and a decrease in the total product release.

[0095] Example 4

[0096] The only difference from Example 1 is that the pretreatment time in step (2) of Example 1 is adjusted to 15 min, 30 min, 45 min, 60 min, 75 min and 90 min.

[0097] The total product release of the enzymatic pretreated polyester is shown in Table 5:

[0098] Table 5 Effect of pretreatment time on total product release

[0099] Pretreatment time (min) 15 30 45 60 75 90 Total product release (mg / L) 83.03 117.13 150.51 227.06 297.99 305.05

[0100] The amount of total enzymatic hydrolysis product released increased with increasing pretreatment time. The maximum amount of enzymatic hydrolysis product release was reached at 75 minutes. Further extending the pretreatment time to 90 minutes resulted in a flattening of the amount, with little change. This suggests that increasing the pretreatment time during CHCl / EA pretreatment can promote the decomposition of polyester macromolecules.

[0101] Comparative Example 5

[0102] The only difference from Example 1 is that the CHCl / EA in step (2) of Example 1 is replaced by a CHCl / EA aqueous solution, so that the CHCl / EA concentrations are 0.2 g / mL, 0.4 g / mL, 0.6 g / mL, 0.8 g / mL, and 0.9 g / mL, respectively.

[0103] The total product release of the enzymatic pretreated polyester is shown in Table 6:

[0104] Table 6 Effect of CHCl / EA concentration on total product release

[0105] CHCl / EA concentration (g / mL) 0.2 0.4 0.6 0.8 0.9 Example 1 Total product release (mg / L) 70.94 140.91 179.70 227.65 265.46 297.99

[0106] Table 6 shows that pretreatment of polyester with a CHCl / EA concentration of 0.2 g / mL resulted in only a small increase in the total amount of enzymatic hydrolysis products released. However, treatment with a CHCl / EA concentration exceeding 0.4 g / mL resulted in superior enzymatic hydrolysis of the polyester. This is because excessive water content may disrupt the hydrogen bonding network of the solvent, resulting in poor pretreatment effectiveness and, consequently, a minimal increase in enzymatic hydrolysis.

[0107] The embodiments provided above are not intended to limit the scope of the present invention, nor are the steps described to limit their execution order. Any obvious improvements to the present invention made by those skilled in the art in combination with existing common knowledge shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for improving the enzymatic hydrolysis efficiency of polyester by using alkaline deep eutectic solvent pretreatment, characterized in that: Including steps: (1) mixing a hydrogen bond donor and a hydrogen bond acceptor, heating and stirring until clear and transparent to obtain a deep eutectic solvent; (2) soaking polyester with a low eutectic solvent, separating the polyester, and washing with ethanol and deionized water until the pH is neutral to obtain pretreated polyester; (3) Dissolve cutinase in Tris-HCl buffer to obtain an enzymatic solution, immerse the pretreated polyester in the reaction, and then inactivate it.

2. The method according to claim 1, characterized in that In step (1), the hydrogen bond acceptor is choline chloride; and the hydrogen bond donor is one or more of acetic acid, formic acid, lactic acid, glycerol, ethylene glycol, urea, acetamide, monoethanolamine and triethanolamine.

3. The method according to claim 1, characterized in that In step (1), the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1-10.

4. The method according to claim 1, wherein In step (1), the heating and stirring temperature is 80 to 120° C.; and the stirring time is 2 to 8 hours.

5. The method according to claim 1, wherein In step (2), the mass ratio of polyester to low eutectic solvent is 1:15 to 1:

25.

6. The method according to claim 1, characterized in that In step (2), the soaking temperature is 30 to 100° C. and the soaking time is 15 to 180 minutes.

7. The method according to claim 1, characterized in that In step (3), the cutinase activity is 1000-3000 U / mL; the enzyme concentration of the enzymatic solution is 50-200 U / mL; and the cutinase is Humicola insolens cutinase.

8. The method according to claim 1, characterized in that In step (3), the pH of the Tris-HCl buffer is 7.5-8.5, and the concentration is 8-12 mmol / L; the mass ratio of the pretreated polyester to the Tris-HCl buffer is 1:40-60.

9. The method according to claim 1, characterized in that In step (3), the reaction temperature is 45-55° C., and the reaction time is 60-100 h.

10. Use of the method according to claim 1 in the degradation of waste polyester.

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