CN113842597A - Method for improving PET biodegradability by using environment-friendly plasticizer - Google Patents

Abstract

The invention discloses a method for improving the biodegradability of PET (polyethylene terephthalate) by utilizing an environment-friendly plasticizer, wherein a whole-cell biocatalysis system for efficiently degrading PET is constructed by taking dimethyl terephthalate, diethyl terephthalate and the like as the environment-friendly plasticizer. The method comprises the following steps: firstly, putting the refined polyester fabric into a dyeing tank according to the bath ratio of 1: 30, and then adding 3g/L of diethyl terephthalate and 800.5 g/L of Tween serving as a penetrating agent; and then putting the dyeing tank into a dyeing machine, heating to 95 ℃ at a speed of 1.5 ℃/min, keeping for 2h, cooling to 60 ℃ at a speed of 2 ℃/min, finally washing for multiple times by using deionized water, spreading on a glass plate, putting into a 100 ℃ oven, drying, crushing, and preparing a culture medium for biodegradation. The method is simple to operate and energy-saving, can effectively reduce the crystallinity of PET, promotes the high-efficiency biodegradation, can hydrolyze the plasticizer simultaneously in the PET biodegradation process, does not cause further pollution to the environment, and meets the sustainable development requirement of ecological dyeing and finishing.

Description

Method for improving PET biodegradability by using environment-friendly plasticizer

Technical Field

The invention relates to a polyester degradation treatment method, in particular to a PET high-efficiency biodegradation method, and belongs to the field of polyester textile processing.

Technical Field

Micro-plastics, particularly the more common polyethylene terephthalate (PET) micro-plastic, are threatening the safety of the ecosystem in various ways. Biodegradation is considered to be the safest and thorough method for solving the pollution of PET micro plastic, but PET has certain biodegradability due to high crystallinity, compact structure and strong surface hydrophobicity. In order to improve the biodegradation efficiency of PET micro plastic, the important content of recent research on reducing the crystallinity of PET is.

Traditional plasticizing small molecules such as wintergreen oil, methylnaphthalene, o-phenylphenol and the like are ideal low-temperature plasticizing aids, but with the development of PET biodegradation, the defects of high toxicity and difficult biodegradation of the plasticizers gradually appear. After the plasticizer acts on PET, the environment is further polluted, and the activity of PET degrading bacteria is reduced, so that the PET is prevented from being degraded by whole-cell microorganisms.

Aiming at the problems of low PET biodegradation efficiency and the like, the invention utilizes micromolecule auxiliary agents (diethyl terephthalate, dimethyl terephthalate and the like) with similar structures with polyethylene terephthalate to plasticize PET, thereby reducing the interaction among PET macromolecular chains, leading hydrolytic enzymes secreted by microorganisms to be capable of efficiently acting on substrates and finally achieving the effect of thorough PET biodegradation. The environmental-friendly plasticizer micromolecules entering the polymer molecules are similar to PET in structure, so that PET is attacked by hydrolase secreted by microorganisms while biodegradation is carried out, and finally CO is used₂、H₂And discharging inorganic substances such as O and the like. The invention obtains inspiration from the traditional polyester carrier dyeing method, combines the plasticization of fabrics, the rapid diffusion of dye molecules and the biodegradation, and innovates a clean biodegradable PET mode with low energy consumption and no pollution.

Disclosure of Invention

The invention aims to solve the technical problem of low PET biodegradation efficiency and provides a method for improving PET biodegradability based on an environment-friendly plasticizer. The method has simple processing technology, the used environment-friendly plasticizer has a structure similar to that of PET, has certain affinity to PET, can be further degraded by a whole-cell catalyst, and has no pollution to the environment.

The technical scheme adopted by the invention is as follows: a method for improving PET biodegradability based on an environment-friendly plasticizer is characterized by comprising the following steps:

(1) polyester fiber refining: firstly, the polyester fabric is placed in a solution with a bath ratio of 1: 20 and containing 5g/L of Tween 80 and 4g/L of sodium carbonate and treated at 98 ℃ for 30min for refining treatment so as to remove residual grease on the surface. Then, the glass plate was washed with deionized water several times, laid flat on the glass plate, and dried in an oven at 100 ℃. And finally, placing the polyester fabric in a constant temperature and humidity box (21 +/-1 ℃, 60 +/-2%) for balancing for 24 hours for later steps.

(2) Preparation of the plasticizing system: placing the refined polyester fabric in a dyeing tank with a bath ratio of 1: 30 and containing 3g/L of environment-friendly plasticizer and 800.5 g/L of penetrating agent Tween.

(3) And (3) plasticizing process: and (3) placing the dyeing tank in the step (2) in a dyeing machine, heating to 95 ℃ at the speed of 1.5 ℃/min, keeping for 2h, cooling to 60 ℃ at the speed of 2 ℃/min, washing with deionized water for multiple times, spreading on a glass plate, and drying in an oven at 100 ℃ for later use.

(4) PET crushing: firstly, cutting a polyester fabric into pieces, and freeze-drying the cut polyester fabric pieces for 5 hours at the temperature of minus 40 ℃ in a freeze dryer; then, the plastic is quickly placed in an ultracentrifugal cutting instrument and cut into micro plastic sizes, and after washing for multiple times by deionized water, the plastic is dried for preparing a culture medium.

(5) Biodegradation of PET: firstly, preparing a culture medium according to a formula, and sterilizing at high temperature and high pressure; then, cooling to room temperature on an ultra-clean bench, and transferring microorganisms; finally, the cells were cultured on a constant temperature shaker at 37 ℃ and 140 rmp. Every 3 days, 30% of the volume of the fermentation broth was replaced and degradation continued for 60 days. The formula of the culture medium is as follows: 1.00g/L of ammonium chloride, 3.00g/L of potassium dihydrogen phosphate, 7.00g/L of disodium hydrogen phosphate, 0.50g/L of sodium chloride, 0.25g/L, PET1 g/1 g/L of magnesium sulfate heptahydrate, 40.0 mu g/L of copper sulfate pentahydrate, 0.2 mu g/L of ferric chloride hexahydrate, 0.4 mu g/L of manganese sulfate pentahydrate, 0.4 mu g/L of zinc chloride, 0.2 mu g/L of ammonium molybdate heptahydrate and 0.5 mu g/L of boric acid.

Preferably, the method comprises the following steps: the environment-friendly plasticizer selected in the step (2) is diethyl terephthalate.

Due to the adoption of the technical scheme, the method has the following beneficial effects:

(1) the plasticizer has a small molecular structure similar to that of PET, so that the plasticizer has certain affinity and can be diffused into the PET molecular structure in a large amount in a short time, and a good plasticizing effect is achieved.

(2) Because the plasticizer has low toxicity and even no toxicity, the PET is degraded in a whole-cell biocatalysis way, and meanwhile, the PET can be hydrolyzed into inorganic matters by extracellular enzymes secreted by microorganisms and discharged, so that the plasticizer is environment-friendly and cannot cause further pollution.

(3) The entrance of small molecules of the plasticizer destroys the interaction between PET molecular chains, so that the structure becomes more relaxed, and extracellular enzymes secreted by microorganisms are favorably specifically combined with PET, thereby promoting the degradation reaction.

Detailed Description

The invention is further described below by means of specific embodiments. Unless otherwise specified, technical means not described in the embodiments may be implemented in a manner well known to those skilled in the art. In addition, the embodiments should be considered illustrative, and not restrictive, of the scope of the invention, which is defined solely by the claims. It will be apparent to those skilled in the art that various modifications, substitutions, and improvements in the materials, amounts, dimensions, and shapes of the embodiments disclosed herein may be made without departing from the spirit and scope of the invention, and the invention is to be limited only by the specific parameters set forth herein as the scope of the invention is to be determined with the permissible error.

Example 1

(1) Polyester fiber refining: firstly, the polyester fabric is placed in a solution with a bath ratio of 1: 20 and containing 5g/L of Tween 80 and 4g/L of sodium carbonate and treated at 98 ℃ for 30min for refining treatment so as to remove residual grease on the surface. Then, the glass plate was washed with deionized water several times, laid flat on the glass plate, and dried in an oven at 100 ℃. And finally, placing the polyester fabric in a constant temperature and humidity box (21 +/-1 ℃, 60 +/-2%) for balancing for 24 hours for later steps.

(2) Preparation of the plasticizing system: placing the refined polyester fabric in a dyeing tank with a bath ratio of 1: 30 and containing 3g/L of dimethyl terephthalate and 800.5 g/L of Tween serving as a penetrating agent.

(3) And (3) plasticizing process: and (3) placing the dyeing tank in the step (2) in a dyeing machine, heating to 95 ℃ at the speed of 1.5 ℃/min, keeping for 2h, cooling to 60 ℃ at the speed of 2 ℃/min, washing with deionized water for multiple times, spreading on a glass plate, and drying in an oven at 100 ℃ for later use.

(4) PET crushing: firstly, cutting a polyester fabric into pieces, and freeze-drying the cut polyester fabric pieces for 5 hours at the temperature of minus 40 ℃ in a freeze dryer; then, the plastic is quickly placed in an ultracentrifugal cutting instrument and cut into micro plastic sizes, and after washing for multiple times by deionized water, the plastic is dried for preparing a culture medium.

(5) Biodegradation of PET: firstly, preparing a culture medium according to a formula, and sterilizing at high temperature and high pressure; then, cooling to room temperature on an ultra-clean bench, and transferring microorganisms; finally, the cells were cultured on a constant temperature shaker at 37 ℃ and 140 rmp. Every 3 days, 30% of the volume of the fermentation broth was replaced and degradation continued for 60 days. The formula of the culture medium is as follows: 1.00g/L of ammonium chloride, 3.00g/L of potassium dihydrogen phosphate, 7.00g/L of disodium hydrogen phosphate, 0.50g/L of sodium chloride, 0.25g/L, PET1 g/1 g/L of magnesium sulfate heptahydrate, 40.0 mu g/L of copper sulfate pentahydrate, 0.2 mu g/L of ferric chloride hexahydrate, 0.4 mu g/L of manganese sulfate pentahydrate, 0.4 mu g/L of zinc chloride, 0.2 mu g/L of ammonium molybdate heptahydrate and 0.5 mu g/L of boric acid.

Example 2

(1) Polyester fiber refining: firstly, the polyester fabric is placed in a solution with a bath ratio of 1: 20 and containing 5g/L of Tween 80 and 4g/L of sodium carbonate and treated at 98 ℃ for 30min for refining treatment so as to remove residual grease on the surface. Then, the glass plate was washed with deionized water several times, laid flat on the glass plate, and dried in an oven at 100 ℃. And finally, placing the polyester fabric in a constant temperature and humidity box (21 +/-1 ℃, 60 +/-2%) for balancing for 24 hours for later steps.

(2) Preparation of the plasticizing system: placing the refined polyester fabric in a dyeing tank with a bath ratio of 1: 30 and containing 3g/L of diethyl terephthalate and 800.5 g/L of Tween serving as a penetrating agent.

(3) And (3) plasticizing process: and (3) placing the dyeing tank in the step (2) in a dyeing machine, heating to 95 ℃ at the speed of 1.5 ℃/min, keeping for 2h, cooling to 60 ℃ at the speed of 2 ℃/min, washing with deionized water for multiple times, spreading on a glass plate, and drying in an oven at 100 ℃ for later use.

(4) PET crushing: firstly, cutting a polyester fabric into pieces, and freeze-drying the cut polyester fabric pieces for 5 hours at the temperature of minus 40 ℃ in a freeze dryer; then, the plastic is quickly placed in an ultracentrifugal cutting instrument and cut into micro plastic sizes, and after washing for multiple times by deionized water, the plastic is dried for preparing a culture medium.

(5) Biodegradation of PET: firstly, preparing a culture medium according to a formula, and sterilizing at high temperature and high pressure; then, cooling to room temperature on an ultra-clean bench, and transferring microorganisms; finally, the cells were cultured on a constant temperature shaker at 37 ℃ and 140 rmp. Every 3 days, 30% of the volume of the fermentation broth was replaced and degradation continued for 60 days. The formula of the culture medium is as follows: 1.00g/L of ammonium chloride, 3.00g/L of potassium dihydrogen phosphate, 7.00g/L of disodium hydrogen phosphate, 0.50g/L of sodium chloride, 0.25g/L, PET1g/L of magnesium sulfate heptahydrate, 40.0 mu g/L of copper sulfate pentahydrate, 0.2 mu g/L of ferric chloride hexahydrate, 0.4 mu g/L of manganese sulfate pentahydrate, 0.4 mu g/L of zinc chloride, 0.2 mu g/L of ammonium molybdate heptahydrate and 0.5 mu g/L of boric acid.

Example 3

(1) Polyester fiber refining: firstly, the polyester fabric is placed in a solution with a bath ratio of 1: 20 and containing 5g/L of Tween 80 and 4g/L of sodium carbonate and treated at 98 ℃ for 30min for refining treatment so as to remove residual grease on the surface. Then, the glass plate was washed with deionized water several times, laid flat on the glass plate, and dried in an oven at 100 ℃. And finally, placing the polyester fabric in a constant temperature and humidity box (21 +/-1 ℃, 60 +/-2%) for balancing for 24 hours for later steps.

(2) Preparation of the plasticizing system: putting the refined polyester fabric into a dyeing tank with a bath ratio of 1: 30 and containing 3g/L of methyl p-hydroxybenzoate and 800.5 g/L of Tween as a penetrating agent.

(3) And (3) plasticizing process: and (3) placing the dyeing tank in the step (2) in a dyeing machine, heating to 95 ℃ at the speed of 1.5 ℃/min, keeping for 2h, cooling to 60 ℃ at the speed of 2 ℃/min, washing with deionized water for multiple times, spreading on a glass plate, and drying in an oven at 100 ℃ for later use.

(4) PET crushing: firstly, cutting a polyester fabric into pieces, and freeze-drying the cut polyester fabric pieces for 5 hours at the temperature of minus 40 ℃ in a freeze dryer; then, the plastic is quickly placed in an ultracentrifugal cutting instrument and cut into micro plastic sizes, and after washing for multiple times by deionized water, the plastic is dried for preparing a culture medium.

(5) Biodegradation of PET: firstly, preparing a culture medium according to a formula, and sterilizing at high temperature and high pressure; then, cooling to room temperature on an ultra-clean bench, and transferring microorganisms; finally, the cells were cultured on a constant temperature shaker at 37 ℃ and 140 rmp. Every 3 days, 30% of the volume of the fermentation broth was replaced and degradation continued for 60 days. The formula of the culture medium is as follows: 1.00g/L of ammonium chloride, 3.00g/L of potassium dihydrogen phosphate, 7.00g/L of disodium hydrogen phosphate, 0.50g/L of sodium chloride, 0.25g/L, PET1g/L of magnesium sulfate heptahydrate, 40.0 mu g/L of copper sulfate pentahydrate, 0.2 mu g/L of ferric chloride hexahydrate, 0.4 mu g/L of manganese sulfate pentahydrate, 0.4 mu g/L of zinc chloride, 0.2 mu g/L of ammonium molybdate heptahydrate and 0.5 mu g/L of boric acid.

The above is only a specific embodiment of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions or modifications made on the basis of the present invention to solve the same technical problems and achieve the same technical effects are all covered in the protection scope of the present invention.

Claims (1)

1. A method for improving the biodegradability of PET by using an environment-friendly plasticizer is characterized by comprising the following steps:

(1) polyester fiber refining: firstly, the polyester fabric is placed in a solution with a bath ratio of 1: 20 and containing 5g/L of Tween 80 and 4g/L of sodium carbonate and treated at 98 ℃ for 30min for refining treatment so as to remove residual grease on the surface. Then, the glass plate was washed with deionized water several times, laid flat on the glass plate, and dried in an oven at 100 ℃. And finally, placing the polyester fabric in a constant temperature and humidity box (21 +/-1 ℃, 60 +/-2%) for balancing for 24 hours for later steps.

(2) Preparation of the plasticizing system: placing the refined polyester fabric in a dyeing tank with a bath ratio of 1: 30 and containing 3g/L of environment-friendly plasticizer (diethyl terephthalate and methyl p-hydroxybenzoate) and 800.5 g/L of penetrating agent Tween.

(3) And (3) plasticizing process: and (3) placing the dyeing tank in the step (2) in a dyeing machine, heating to 95 ℃ at the speed of 1.5 ℃/min, keeping for 2h, cooling to 60 ℃ at the speed of 2 ℃/min, washing with deionized water for multiple times, spreading on a glass plate, and drying in an oven at 100 ℃ for later use.

(4) PET crushing: firstly, cutting a polyester fabric into pieces, and freeze-drying the cut polyester fabric pieces for 5 hours at the temperature of minus 40 ℃ in a freeze dryer; then, the plastic is quickly placed in an ultracentrifugal cutting instrument and cut into micro plastic sizes, and after washing for multiple times by deionized water, the plastic is dried for preparing a culture medium.

(5) Biodegradation of PET: firstly, preparing a culture medium according to a formula, and sterilizing at high temperature and high pressure; then, cooling to room temperature on an ultra-clean bench, and transferring microorganisms; finally, the cells were cultured on a constant temperature shaker at 37 ℃ and 140 rmp. Every 3 days, 30% of the volume of the fermentation broth was replaced and degradation continued for 60 days. The formula of the culture medium is as follows: 1.00g/L of ammonium chloride, 3.00g/L of potassium dihydrogen phosphate, 7.00g/L of disodium hydrogen phosphate, 0.50g/L of sodium chloride, 0.25g/L, PET1 g/1 g/L of magnesium sulfate heptahydrate, 40.0 mu g/L of copper sulfate pentahydrate, 0.2 mu g/L of ferric chloride hexahydrate, 0.4 mu g/L of manganese sulfate pentahydrate, 0.4 mu g/L of zinc chloride, 0.2 mu g/L of ammonium molybdate heptahydrate and 0.5 mu g/L of boric acid.