Synergistic chemo‐enzymatic hydrolysis of poly(ethylene terephthalate) from textile waste

• Published in: Microbial biotechnology Vol. 10; no. 6; pp. 1376 - 1383
• Main Authors: Quartinello, Felice, Vajnhandl, Simona, Volmajer Valh, Julija, Farmer, Thomas J., Vončina, Bojana, Lobnik, Alexandra, Herrero Acero, Enrique, Pellis, Alessandro, Guebitz, Georg M.
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.11.2017; John Wiley and Sons Inc; Wiley
• Subjects: Biocatalysis; Carboxylic Ester Hydrolases - chemistry; Chemical treatment; Chemicals; Chromatography; Cutinase; Economic conditions; Emission standards; Environmental protection; Enzymes; Ethylene; Ethylene glycol; Fourier transforms; Fungal Proteins - chemistry; Humicola insolens; Hydrolysis; Industrial Waste - analysis; NMR; Nuclear magnetic resonance; Oligomers; Organic chemistry; Polyester resins; Polyesters; Polyethylene terephthalate; Polyethylene Terephthalates - chemistry; Recycling; Sordariales - enzymology; Terephthalic acid; Textile industry; Textile industry wastes; Textiles; Textiles - analysis; Viscosity
• ISSN: 1751-7915; 1751-7915
• DOI: 10.1111/1751-7915.12734

Summary Due to the rising global environment protection awareness, recycling strategies that comply with the circular economy principles are needed. Polyesters are among the most used materials in the textile industry; therefore, achieving a complete poly(ethylene terephthalate) (PET) hydrolysis in an environmentally friendly way is a current challenge. In this work, a chemo‐enzymatic treatment was developed to recover the PET building blocks, namely terephthalic acid (TA) and ethylene glycol. To monitor the monomer and oligomer content in solid samples, a Fourier‐transformed Raman method was successfully developed. A shift of the free carboxylic groups (1632 cm−1) of TA into the deprotonated state (1604 and 1398 cm−1) was observed and bands at 1728 and 1398 cm−1 were used to assess purity of TA after the chemo‐enzymatic PET hydrolysis. The chemical treatment, performed under neutral conditions (T = 250 °C, P = 40 bar), led to conversion of PET into 85% TA and small oligomers. The latter were hydrolysed in a second step using the Humicola insolens cutinase (HiC) yielding 97% pure TA, therefore comparable with the commercial synthesis‐grade TA (98%). A synergic chemo‐enzymatic depolymerization of poly(ethylene terephthalate) (PET) from textile waste was successfully carried out yielding 97% pure terephthalic acid that could be used for PET re‐synthesis.