Up-cycling of PET (polyethylene terephthalate) to the biodegradable plastic PHA (polyhydroxyalkanoate)
| Autor: | Chris M. Keely, Shane T. Kenny, Trevor Woods, Jasmina Nikodinovic Runic, Walter Kaminsky, Ramesh Babu, Werner J. Blau, Kevin E. O’Connor |
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| Rok vydání: | 2008 |
| Předmět: |
business.product_category
Magnetic Resonance Spectroscopy Phthalic Acids 02 engineering and technology Polyhydroxyalkanoates 03 medical and health sciences chemistry.chemical_compound Soil Pseudomonas Bottle Polyethylene terephthalate Environmental Chemistry 030304 developmental biology chemistry.chemical_classification Terephthalic acid 0303 health sciences biology Waste management Polyethylene Terephthalates Hydrolysis Temperature General Chemistry Polymer 021001 nanoscience & nanotechnology biology.organism_classification 6. Clean water Monomer Biodegradation Environmental chemistry Biodegradable plastic 0210 nano-technology business Plastics Bacteria Nuclear chemistry |
| Zdroj: | Environmental Science and Technology |
| ISSN: | 0013-936X |
| Popis: | The conversion of the petrochemical polymer polyethylene terephthalate (PET) to a biodegradable plastic polyhydroxyalkanoate (PHA) is described here. PET was pyrolised at 450 degrees C resulting in the production of a solid, liquid, and gaseous fraction. The liquid and gaseous fractions were burnt for energy recovery, whereas the solid fraction terephthalic acid (TA) was used as the feedstock for bacterial production of PHA. Strains previously reported to grow on TA were unable to accumulate PHA. We therefore isolated bacteria from soil exposed to PET granules at a PET bottle processing plant. From the 32 strains isolated, three strains capable of accumulation of medium chain length PHA (mclPHA) from TA as a sole source of carbon and energy were selected for further study. These isolates were identified using 16S rDNA techniques as P. putida (GO16), P. putida (GO19), and P. frederiksbergensis (GO23). P. putida GO16 and GO19 accumulate PHA composed predominantly of a 3-hydroxydecanoic acid monomer while P. frederiksbergensis GO23 accumulates 3-hydroxydecanoic acid as the predominant monomer with increased amounts of 3-hydroxydodecanoic acid and 3-hydroxydodecenoic acid compared to the other two strains. PHA was detected in all three strains when nitrogen depleted below detectable levels in the growth medium. Strains GO16 and GO19 accumulate PHA at a maximal rate of approximately 8.4 mg PHA/l/h for 12 h before the rate of PHA accumulation decreased dramatically. Strain GO23 accumulates PHA at a lower maximal rate of 4.4 mg PHA/l/h but there was no slow down in the rate of PHA accumulation over time. Each of the PHA polymers is a thermoplastic with the onset of thermal degradation occurring around 308 degrees C with the complete degradation occurring by 370 degrees C. The molecular weight ranged from 74 to 123 kDa. X-ray diffraction indicated crystallinity of the order of 18-31%. Thermal analysis shows a low glass transition (-53 degrees C) with a broad melting endotherm between 0 and 45 degrees C. |
| Databáze: | OpenAIRE |
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