Optimizing pyrolysis process parameters of plastic grocery bag, with mass–energy assessment and characterization of oil at optimal condition

The widespread usage of plastic grocery bags, as well as their non-biodegradability, has turned out to be a stern reason for waste generation. With regard to plastic grocery bag disposal, pyrolysis is an encouraging solution that addresses the energy crisis issue as well. This study examined the interactive influences of pyrolysis temperature, residence time, and nitrogen flow for plastic grocery bag pyrolysis to optimize waste plastic oil yield by the Grey–Fuzzy–Taguchi method. Additionally, mass–energy assessment and characterization were done for the waste plastic oil, extracted at the optimal parametric condition. The optimal parametric combination was: temperature 400 °C, time 360 min, and nitrogen flow rate 20 ml/min. The liquid yield at optimal condition was 78.57%, and a minimal error (2.53%) between the predicted and experimental grey fuzzy grade was observed. The oil achieved at optimal condition showed a high hydrocarbon content with a higher heating value of 46,685 kJ/kg. The values of mass ratio, energy ratio, energy efficiency, and energy consumption ratio for the liquid oil were 0.79, 0.89, 0.63, and 0.47, respectively, which indicate the energy favorability for plastic grocery bag pyrolysis. FT-IR results demonstrated mainly the existence of alkene and alkane functional groups in the waste plastic oil. GC–MS results revealed that the oil contains mainly light and middle fractions of 26.4% and 62.7%, respectively, with a smaller proportion (10.9%) of heavy fraction. Finally, the optimum parametric combination can be considered a useful condition for extracting quality fuel from plastic grocery bags.