Experimental investigation of products from thermal treatment of real-world mixed single-use and multi-layered waste plastics.

The usage and disposal of highly abundant single-use and multilayered plastics contribute to significant ecological problems. The thermochemical recovery of these plastics to useful products and chemicals provides opportunity for positive economic and environmental impacts. Most previous research use idealised and unrepresentative feedstocks. To address this, various mixed waste plastics collected from the rejected fraction of a municipal waste recovery facility in Ghana were pyrolyzed at varying temperatures of 450, 500 and 550 °C and their yields compared. The obtained chemical products were analysed using several different techniques. Energy and carbon balances of the processes were produced using the CHNS and energy content of the oil fraction and the compositional results of the pyrolysis gas fraction, the latter of which was measured by Gas Chromatography Thermal Conductivity Detection (GC-TCD). The oils were further assessed via Gas Chromatography Mass Spectrometry (GC-MS) to identify the available valuable compounds. The formed oil contained approximately 40% light hydrocarbons (C6 - C11), 18% middle hydrocarbons (C11 - C16) and 42% heavy hydrocarbon compounds (C16+). The optimal oil yield of 65.9 ± 0.5% and low heating value of 44.7 ± 0.1 MJ/kg for single-use plastics were recorded at highest heating temperatures of 550 and 500 °C, respectively. The findings provide indication that pyrolysis is a fitting solution for energy recovery from waste plastics.