Hydrolysis in PET Bottle Chemical Recycling

Genetically engineering Pseudomonas putida bacteria to selectively degrade and convert polyethylene terephthalate (PET) plastic into valuable chemicals. The engineered bacteria express PETase and MHETase enzymes from Ideonella sakaiensis to break down PET into terephthalate and ethylene glycol. They also have genes for transporting and metabolizing terephthalate. This allows converting the PET deconstruction products into chemicals like beta-ketoadipate. The engineered bacteria can grow on PET as the sole carbon source. The strategy involves using PETase and MHETase to degrade PET into monomers, then converting those monomers into useful chemicals in the engineered bacteria.

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Method to efficiently recycle mixed plastic waste containing a high proportion of heteroatom-containing polymers like PET and PA by extracting the heteroatom-containing components during melting. The process involves feeding mixed plastic waste with water and alkali into an extruder. The melting and degradation of the heteroatom-containing polymers releases the heteroatoms like amide, ester, carbamate, and carbonate bonds, which can be removed from the melt. The remaining pure hydrocarbon plastic can be further processed.

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Esterases with improved activity and thermostability for breaking down polyester plastics like PET. The enzymes have mutations compared to a reference sequence like SEQ ID No. 1. Examples of mutations are L210A/C/D/E/G/H/I/K/M/N/P/Q/R/S/T/V/W/Y, R205C, S251C, Q95G/P, G136A, T169Q, V172I, S184E, N213M/D. These mutations can be combined to create customized esterases with optimized polyester degradation activity and stability.

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Enzymatic depolymerization of polymers like PET and polycarbonate using moist-solid reaction mixtures. The method involves combining the polymer with an enzyme like cutinase or esterase and optional additives, then mechanochemically milling or mixing the mixture. The enzyme-catalyzed reaction is allowed to proceed by aging the mixture. This allows direct depolymerization of high crystallinity polymers like PET without pre-milling or solvent. The enzyme can be wild-type or engineered.

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Neutral hydrolysis method for waste polyester without waste liquid discharge. The method involves a two-step process: (1) alcohol treatment with ethylene glycol to partially depolymerize and dissolve impurities in the waste polyester, (2) hydrolysis in ethylene glycol to completely depolymerize and separate the polyester into pure terephthalic acid and ethylene glycol. This allows recycling the polyester without generating waste water. The alcohol treatment reduces polyester molecular weight and impurity content, making hydrolysis milder and more efficient.

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A selective and scalable chemical recycling process for polyethylene terephthalate (PET) waste that avoids the high energy requirements and complex technologies needed for depolymerization of PET. The process involves reacting PET with a nucleophile in excess, catalyzed by a base and alkaline metal salt, to selectively decompose the PET into its monomers. The process conditions are mild compared to existing techniques.

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Method for recycling waste polyester like PET bottles into usable polyester by alcoholysis with ethylene glycol catalyzed by a two-component catalyst of nitrogen-containing polycyclic organic matter and metal salts like zinc acetate. The catalyst synergistically accelerates ester bond cleavage compared to single components. The timing of adding the nitrogen compound is critical to avoid decomposition. The method involves heating crushed PET in ethylene glycol with metal salt, then adding the nitrogen catalyst. The alcoholysis completes when PET disappears. This gives high-purity recycled BHET for repolymerization.

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Method to recycle waste PET into higher value PETG/PCTG copolyester using mixed alcohol depolymerization followed by polycondensation. The recycling process involves alcoholysis of waste PET using a catalyst to break down the polymer into BHET/BHCT monomers and oligomers using a mixture of ethylene glycol (EG) and 1,4-cyclohexanedimethanol (CHDM). These depolymerization products are then polycondensed using a catalyst to make PETG/PCTG copolyester with properties like improved light transmittance, environmental friendliness, and heat resistance compared to virgin PET.

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A double depolymerization method for recycling waste polyester like PET that involves using two different depolymerization techniques in series to improve product yield and purity compared to single methods. The first step is an initial depolymerization using a method like alkaline hydrolysis or methanolysis to partially break down the polyester into monomers or oligomers. The second step is a final depolymerization using a different method like glycolysis or alcoholysis to fully depolymerize the partially broken polymer into monomers. This two-step process allows higher yields and better purification compared to using just one depolymerization method.

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A continuous process for recycling PET plastic waste into high quality regenerated PET. The process involves alcoholysis of the waste PET fragments using ethylene glycol (EG) and a catalyst. The alcoholysis is carried out in two reactors with controlled conditions to depolymerize the oligomers and remove excess EG. The final repolymerization step is done in a separate reactor. The continuous process allows efficient recycling with good economics and high quality regenerated PET. The lower EG to PET ratio and homogeneous reaction conditions in the alcoholysis reactors enable rapid dissolution and depolymerization of the PET fragments.

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A two-component mixed metal catalyst system for efficiently recycling waste polyethylene terephthalate (PET) using alcoholysis. The catalyst contains zinc acetate and an alkali metal hydroxide like sodium or potassium hydroxide. The zinc acetate forms a complex with the highly polar ethylene glycol solvent, and the alkali metal hydroxide provides highly alkaline conditions. This two-component catalyst synergistically improves PET alcoholysis efficiency and yield by enhancing the nucleophilicity of the alcohol solvent and strengthening the hydrogen bonding between the solvent and catalyst.

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A method for recycling waste polyethylene terephthalate (PET) using zinc oxide nanoparticles as a catalyst for alcoholysis. The method involves using a zinc oxide nanoparticle catalyst to convert waste PET into bishydroxyethyl terephthalate (BHET) using ethylene glycol as the solvent. The zinc oxide nanoparticle catalyst is prepared by mixing zinc acetate and sodium hydroxide in water. The catalyst addition, ethylene glycol-to-PET ratio, temperature, and time are optimized to improve the PET conversion and BHET yield.

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Recycling of polyethylene terephthalate (PET) waste into new PET using a two-step process that involves partial depolymerization followed by complete depolymerization. This reduces the time and ethylene glycol required compared to direct depolymerization. The partial depolymerization step involves heating PET with excess ethylene glycol to 200-250°C to produce partially depolymerized PET. This intermediate is then depolymerized with ethylene glycol and catalyst at 170-200°C to form bis(2-hydroxyethyl) terephthalate (BHET). The BHET is purified and polymerized to regenerate PET.

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A method for recycling polyethylene terephthalate (PET) plastic that involves depolymerizing it using an electrolysis cell with an alkali metal glycolate solution. The PET is reacted with the glycolate solution to produce bis-2-hydroxyethyl terephthalate (BHET) at high yields. The method involves using an electrolysis cell with alkali metal glycolate solution instead of acid to depolymerize PET. The cell contains an alkali metal glycolate solution made by electrolysis. This method allows recycling PET into BHET with higher yields and less waste compared to other methods.

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Process for depolymerizing PET plastics into BHET using sodium or potassium glycolate obtained by reactive distillation. The process involves reacting glycol with alkali metal alcoholate like sodium or potassium ethoxide in a reactive distillation column. This produces a crude product stream containing glycolate, water, alcohol, and unreacted alcoholate. The glycolate can then be separated and used for depolymerizing PET to BHET. The reactive distillation provides higher yields of BHET compared to using glycolate directly. After depolymerization, the BHET can be polymerized again into PET if desired. This provides a recycling loop for PET plastics.

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Mild, efficient and selective recycling method for waste polyester materials that involves hydrolysis to break down the polyester into monomers. The process involves mixing the waste polyester with glycol, water, a polar aprotic solvent or ether, and an alkaline catalyst. The reaction forms acidic degradation products that precipitate out. This selective hydrolysis allows gentle and efficient recycling of complex waste polyester materials like bottles and textiles, compared to incineration or landfilling.

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Selective depolymerization of waste polyester like PET using aqueous metal salts to produce depolymerized monomers and oligomers. This allows recycling of waste plastics into new polymers without significant degradation. The process involves heating waste polyester in metal salt solution to break down the polymer. The depolymerized products can then be polymerized again to make renewable polyesters. The metal salt residue is removed. This selective depolymerization avoids the energy-intensive separation steps of conventional methods.

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Mild and selective depolymerization of waste polyester and its blended textiles to recover the polyester without degrading the non-polyester fibers. The process uses a solvent mixture of alcohols and aprotic solvents, catalyzed by alkaline bases, to hydrolyze or alcoholysis decompose the polyester selectively. This avoids harsh conditions that degrade other fibers. The undepolymerized non-polyester fibers are separated and recycled, while the polyester decomposes into recoverable monomers.

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Catalyzing low-temperature degradation of waste polyethylene terephthalate (PET) into terephthalic acid and ethylene glycol using alkaline earth metal hydroxides or oxides as catalysts. The catalyst allows controlled degradation of PET melt at temperatures as low as 230-350°C. Adding water after catalytic degradation hydrolyzes the intermediate monovinyl terephthalate to generate the final products. This method recovers terephthalic acid and ethylene glycol from waste PET using simple, low-energy, and catalyst-recoverable degradation.

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Recovering waste polyester like PET bottles by alcoholysis using ionic liquids as catalysts instead of metal catalysts. This provides a green and efficient method to recycle waste PET into new polyester products without degrading the quality. The ionic liquids catalyze the reaction of waste PET with ethylene glycol at mild conditions to produce BHET, the main component of PET. The ionic liquid catalysts like 1-butyl-3-methylimidazolium acetate have better performance compared to metal catalysts in terms of PET conversion rate and BHET productive rate.

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Chemical recycling method for waste polyester like old PET bottles and textiles to produce high-purity polyester chips. The method involves pretreating the waste polyester to remove impurities, followed by depolymerization using a mixture of diols and alkane solvents. The depolymerization is catalyzed by an initiator. The resulting polyester monomer is crystallized, filtered, and dried to make high-purity polyester chips. This yields over 97% compared to traditional methods that struggle to exceed 70%. The pretreatment removes heavy metals, pigments, and other impurities, ensuring high-quality recycled polyester chips.

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A method to degrade polyester plastics like PET into high-purity monomers and esters using organic acids as solvent and catalyst. The degradation reaction involves mixing waste polyester with an organic acid like acetic acid to depolymerize the polyester into terephthalic acid (TPA) and esters like ethylene glycol diacetate (EGDA) and ethylene glycol monoacetate (EGMA). The degradation products can be purified and used for repolymerization or other applications. The organic acid solvent allows efficient depolymerization and recovery of the monomers and esters compared to water-based methods.

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A method to recycle high-viscosity PET like water bottle containers without using solvents. The method involves melting the PET, adding an alkali slurry with ethylene glycol, and reacting the melted PET in-situ to form alkali terephthalate. This is done continuously in an extruder-like reactor. The alkali terephthalate is then dissolved in water and further reacted with acid to produce terephthalic acid. The extruder-based in-situ reaction avoids the need for solvents to decompose high-viscosity PET.

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Recovering high-quality BHET (bisphenol A ethylene terephthalate) from waste polyester products like old textiles and bottles using the unique phase transition properties of BHET crystals. The method involves alcoholysis to convert waste PET into BHET, followed by decompression sublimation and condensation to separate and purify the BHET crystals from impurities. This allows efficient recycling of waste PET into high-value BHET without needing expensive decolorization steps.

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A process for recycling colored and opaque polyester waste like plastic bottles into monomers that can be reused to make new polyester. The process involves optimizing a feedstock conditioning step to break down the polyester before further depolymerization. The conditioning step uses extrusion to heat and mix the feedstock for a short time. This breaks down the polyester structure and reduces viscosity. The conditioned feed is then blended with diol and heavy impurity effluents from later steps. This improves monomer yield and decolorization. The blended feed is glycolyzed to break down the polyester into monomers. The process allows recycling of colored and opaque PET by addressing the challenges of pigment clogging and impurities.

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Chemical recycling method for polyester-based polymer waste like PET that enables recovering high-purity monomers without forming high molecular weight impurities. The recycling involves depolymerizing the waste using a catalyst and alcohol to make a reactant containing monomers. Then, contacting the reactant with an ion exchange resin to remove catalysts and impurities. Finally, separating residual alcohols. This allows directly obtaining monomer-rich solutions with low catalyst and impurity levels compared to conventional recycling.

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Recycling waste PET by directly mixing it with aliphatic polyester or precursor, catalytically inserting the aliphatic repeating units into the PET chain, and then polymerizing under reduced pressure to generate volatile small molecules that can be removed. This simplified chemical conversion process avoids the need to alcoholyze PET into monomers and then react with other components.

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A process for recycling PET plastic that uses a specific catalyst system and conditions to improve the quality of the regenerated PET compared to existing methods. The catalyst system involves a composite of tin, zinc, and silver acetates. It is used in conjunction with mesoporous materials to maximize the catalytic cracking of PET. The optimal conditions for the process are 180-200°C with a catalyst loading of 5g mesoporous material per kg PET. This allows for high conversion and yield of BHET, the desired regenerated PET component, while minimizing metal ion leaching into the reaction media.

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Efficient method to recycle PET waste into high quality polymer suitable for applications like bottles and films. The method involves a series of depolymerization reactors to break down the PET into BHET monomer with high purity. The BHET is then recrystallized using water to separate out impurities like dimers and trimers. This allows direct polymerization of the purified BHET without further purification steps. The integrated recycling process improves efficiency compared to separate depolymerization and purification steps.

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Recycling polyethylene terephthalate (PET) plastic by depolymerizing it into bis(2-hydroxyethyl) terephthalate (BHET) monomers, which can then be repolymerized into new PET. The BHET recycling process involves depolymerizing PET waste using multiple reactors, crystallizing the BHET, and dissolving the crystals in methanol or water to remove impurities. This simplifies PET recycling by avoiding complex purification steps to prepare BHET for repolymerization. The BHET recycling process allows using higher BHET levels in PET production compared to recycling methods that involve glycolysis, which reduces PET yield and requires more feedstock. The recycled BHET with lower impurities allows higher quality PET production compared to gly

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Recycling polyethylene terephthalate (PET) plastic waste into high quality recycled PET that can be used in applications like clear water bottles. The recycling process involves a series of depolymerization reactors to break down the PET into bis(2-hydroxyethyl) terephthalate (BHET). The BHET is then crystallized to separate out impurities like dimers and trimers. This simplified recycling method allows producing PET directly from the recycled BHET without further purification, reducing waste and energy compared to traditional methods. The resulting recycled PET has improved quality for high grade applications like clear bottles.

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Recycling of poly(ethylene terephthalate) (PET) waste into pure bis(2-hydroxyethyl) terephthalate (BHET) monomer using a reusable and recyclable layered double hydroxide (LDH) catalyst. The process involves dissolving PET waste in ethylene glycol solvent and catalyzing the depolymerization reaction with the LDH catalyst containing zinc and titanium precursors. The catalyst can be reused multiple times without significant degradation in conversion and BHET yield.

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Recycling method for mixed plastic waste containing PET and other polymers like BPA-PC. The method involves sequential depolymerization of the mixed plastics using a zinc catalyst, initiated by alcohol compounds, under inert gas protection and without additional solvents. The depolymerization is done at temperatures between 20-300°C. This allows selective breakdown of PET while leaving other polymers intact. The depolymerized PET can be separated and recycled.

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Improved method for depolymerizing polyester waste like PET bottles to recycle it into new polyester. The method involves a conditioning step before depolymerization to break down the polyester feedstock more efficiently. In the conditioning step, the feedstock is extruded at high temperature and mixed with glycol to prepare it for alcoholysis. This step adjusts the diol-to-diester ratio and conditions the polymer for easier depolymerization. The extrusion time is less than 5 hours to avoid repolymerization. The conditioned feedstock is then depolymerized by glycolysis at high temperature and pressure, followed by glycol separation, monomer separation, and decolorization steps.

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A process to recycle waste PET (polyethylene terephthalate) into high-purity regenerated PET using alcoholysis and polycondensation. The process involves treating waste PET with dimethyl terephthalate (DMT) in the presence of a catalyst to produce DMT and ethylene glycol. The DMT is then purified by distillation and crystallization. The purified DMT is polycondensed with ethylene glycol to form recycled PET. This avoids using methanol transesterification and removes the need for decolorization steps. The recycled PET has lower color and is suitable for high-grade applications compared to prior methods.

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A method for recycling polyethylene terephthalate (PET) waste to produce high quality PET suitable for clear and colorless bottles. The method involves depolymerizing PET using ethylene glycol to form bis(2-hydroxyethyl) terephthalate (BHET) monomers. The BHET solution is then purified by decolorization steps using solvents, resins, and decolorizing agents to remove impurities like dimers and trimers. This purified BHET can be used to make new high quality PET without the yellow tint often found in recycled PET. The decolorization steps allow recovering more of the PET feedstock compared to conventional methods that discard the dimers and trimers.

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A recycling system and method for polyethylene terephthalate (PET) that allows efficient recycling of PET waste into high-quality PET with high purity and properties similar to virgin PET. The system involves a multi-step process to clean and break down waste PET into BHET monomers. These monomers are then polymerized to produce recycled PET (rPET) with better quality and properties compared to traditional recycling methods. The key steps include mechanical separation, esterification, glycolysis, filtration, and solid-state polymerization.

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Recycling polyesters such as polyethylene terephthalate. The recycling includes contacting a polyethylene terephthalate-containing feedstock with at least one alcohol in the presence of a depolymerization catalyst and at least one acid or acid precursor, selected from a mineral acid, an organic acid an anhydride and an ester.

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Integrated process for recycling and producing polyester resins using depolymerization and polymerization steps. The process involves recycling used PET by depolymerizing it to monomers, then repolymerizing the monomers to make new PET. The depolymerization step uses the PET feedstock and excess glycol to form diester monomers. The diester effluent is purified and fed back to polymerization. This avoids intermediate steps like crystallization and saves energy compared to separate recycling and virgin resin production.

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Acid-catalyzed hydrolysis of waste PET plastic to recycle it into terephthalic acid and ethylene glycol. The process involves heating crushed PET waste, terephthalic acid, and water under pressure in a reactor. The reaction is catalyzed by terephthalic acid itself. The mixture is filtered, the solid precipitate washed, and the filtrate distilled to separate ethylene glycol and water. The terephthalic acid is recycled as catalyst for further hydrolysis cycles. This allows closed-loop recycling of PET without acid or base waste streams.

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Efficient recycling of post-consumer polyethylene terephthalate (PET) waste into new PET products. The recycling involves partially depolymerizing the PET using heat and ethylene glycol. This breaks down the PET into oligomers. The oligomers are then repolymerized with virgin PET monomers to make new PET. This allows recycling PET waste without needing extensive purification steps. The process involves heating the PET with ethylene glycol at elevated pressures to depolymerize it into oligomers. The oligomers are then mixed with virgin PET monomers and repolymerized.

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Efficiently recycling waste polyester like PET into new polyester using a catalyst and process that speeds up the depolymerization step. The catalyst is a mixture of zinc acetate and sodium ethoxide. It is added to the depolymerization solution along with PET oligomers. The oligomers help dissolve solid PET faster in the liquid phase, accelerating the depolymerization reaction. This synergy between catalyst and oligomers increases the monomer yield compared to using just the catalyst. The faster, more efficient depolymerization allows recycling waste polyester into new polyester more economically and sustainably.

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A method for producing recycled polyester chips with high alcoholysis efficiency and easy catalyst recovery. The method involves using a catalyst system of zinc nicotinate coordination polymer and carboxyl octanol to recycle waste PET bottles into recycled polyester chips. This catalyst system allows efficient alcoholysis of PET into BHET with high alcoholysis efficiency. The catalyst can be easily recovered and reused, improving the overall process efficiency and reducing costs compared to traditional catalysts like zinc chloride.

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Chemical recycling of waste PET that improves the BHET yield and productivity. The recycling includes performing an aminolisis reaction step of reacting waste PET and a reaction solvent of an amine compound under a depolymerization catalyst to produce an amide compound.

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Improved process for depolymerizing polyethylene terephthalate (PET) into its monomers terephthalic acid and ethylene glycol, using a solvent system without external heat. The process involves swelling PET with a non-polar solvent like halogenated solvents, followed by mixing with an ester-degrading agent like alcohol/hydroxide, without heat, to depolymerize PET into the monomers.

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A process to depolymerize polyethylene terephthalate (PET) into terephthalic acid and ethylene glycol without external heat. The process involves swelling PET with a non-polar solvent like chlorinated solvents, followed by mixing with an alcohol-hydroxide drug. This allows degradation of the ester groups and depolymerization into starting materials for PET production.

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A process for making high purity terephthalic acid from waste polyethylene terephthalate (PET) bottles using microwave heating and solvent extraction. The PET is depolymerized by alkaline hydrolysis with microwaves. After depolymerization, the mixture is stirred with water, extracted with an organic solvent, and impurities are removed by contact with a sorbent. The terephthalic acid is then precipitated by acidification and separated. This allows selective separation of terephthalic acid from impurities in the PET depolymerization reaction.

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Recycling waste polyester bottles in whole bottles and application thereof. The recycling includes carrying out three filtering processes on the plastics, and the separated plastics are regenerated from the recovered PET melt.

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Efficiently depolymerizing polyethylene terephthalate (PET) into terephthalic acid and ethylene glycol without applying external heat. The process involves mixing PET with a solvent that swells the polymer, like a halogenated solvent, and an ester-breaking agent like a linear C1-C4 alcohol and a hydroxide. The mixture is agitated for 1 hour to depolymerize PET into starting materials for new PET production.

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Method to recycle mixed waste containing polyester into terephthalic acid, a key precursor for making new polyester. The process involves breaking the waste, depolymerizing the polyester to form disodium terephthalate, decolorizing and separating the disodium terephthalate, then crystallizing the terephthalic acid. The separated waste streams can be further processed into fuel or purified terephthalic acid.

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