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.

Occurrence, toxicity and remediation of polyethylene terephthalate plastics. A review

“…Then, as on heating, the sample liberates volatile organic compounds (VOCs). This technique measures the heating time for produced VOCs, identifies them, and quantifies the compounds produced (Liu et al 2018b). Dümichen et al (2017) used thermal extraction desorption gas chromatography-mass spectroscopy to determine the quantity of organic and inorganic components in the soil matrix, such as ethyl benzoate and vinyl benzoate.…”

“…Divinyl terephthalate, mono-vinyl terephthalate, benzene, toluene and terephthalic acid were the primarily identified products at 435 °C temperature pyrolysis using thermogravimetric analysis-mass spectroscopy analysis (Hujuri et al 2013). It is further explored by Liu et al (2018b) to detect the volatile organic compounds composition during the thermal degradation of PET fibres and popcorn. It was observed that the methylbenzene, styrene, formaldehyde, acetaldehyde and benzaldehyde compounds were present (Liu et al 2018b).…”

“…It is further explored by Liu et al (2018b) to detect the volatile organic compounds composition during the thermal degradation of PET fibres and popcorn. It was observed that the methylbenzene, styrene, formaldehyde, acetaldehyde and benzaldehyde compounds were present (Liu et al 2018b). David et al (2018) explored this technique for the PET micro-plastic quantitative analysis in soil.…”

A review on VOCs from recycled plastics

“…After the washing unit, the polymer is melted utilizing screw extruders. The extrusion unit plays an essential role in the formation of VOC emissions from plastic, as the plastic is melted at high temperatures through the rotating screw, thus facilitating the degradation of the material and the release of breakdown products (S. S. Liu et al, 2019).…”

“…The main drawbacks of reprocessing recycled post-consumer plastic waste is the advanced stage of degradation of the polymer as well as the levels of contaminants in the recycled material . Most of the contaminants present in post-consumer plastic waste are related to organic compounds, including volatile organic compounds (VOCs), some of which have been reported to be of particular concern for human health, such as benzene that was detected in post -consumer recycled PET, as reported by Liu et al (2019). In addition, substances causing unwanted smells have been identified in post-consumer plastics whose origin is related to their previous use phase .…”