Analysis of the Volatile Organic Compounds (VOCs) during the Regeneration of Post-Consumed Poly(Ethylene Terephthalate) Using HS-GC-MS Method

Abstract

VOCs emissions from recycled PET are recognized as one of the major causes of poor healthy condition. Much attention has been increasingly focused on VOCs produced from regenerated PET for their significance in ecological safety. These emissions may be strongly influenced by the raw materials and manufacturing techniques of the recycled PET. However, there is very little published information regarding this issue. The purpose of this study was to examine VOCs releasing from reprocessed productions when exposed to high temperature or other extreme conditions.In this study, we determined and compared VOCs emissions from samples after different manufacturing stages such as PET popcorn, dried PET popcorn, screw melts, undrawed fibers and drawed fibers, including their species and content. To simulate the VOC emissions of samples processed with the high temperature in longer time during screw melting, we investigated VOCs from screw melts utilizing Thermo Gravimetric-Mass Spectrometry (TG-MS) with 90 min in 280°C . We found that: (1) The optimisation of the equilibration procedure for volatile organic compounds was performed and the optimal equilibration conditions were determined to be 30 min at 120°C ; (2) Seven individual VOCs were identified: considerable VOC content changes during the manufacturing process; and the drying was tremendously helpful in reducing the VOC emissions from PET popcorn; formaldehyde, acetaldehyde and TVOC were reduced by 24%, 58% and 50%, respectively after drying; while acetaldehyde, benzene, benzaldehyde and TVOC increased dramatically after screw melting; (3) The VOCs were released at the initial stage of heat preservation (about 5 min) and VOCs content came to the maximum which indicated the almost immediate thermal degradation in screw melting.