Synergistic Effects of Waste Tires, Plastic, and Biomass in Pyro-Oil Production

Abstract

This study explores the potential of converting waste tires, low-density polyethylene (LDPE) waste plastic, biomass (sawdust), and their blends into pyro-oils. Comprehensive analyses, including proximate and ultimate analyses and calorific value (CV) assessments, were conducted to determine the elemental composition, moisture content, ash content, fixed carbon, volatile matter, and energy density of the feedstocks. Thermogravimetric analyses (TG and DTG) assessed the thermal stability and decomposition points, while scanning electron microscopy (SEM) examined the surface characteristics and morphology of the feedstocks and their blends. These characterizations were crucial for evaluating the suitability of the feedstocks for pyrolysis. DTG analysis indicated decomposition temperature ranges of 315–498 °C for waste tires, 420–534 °C for waste plastic, 224–413 °C for biomass, and 220–527 °C for the blend. FTIR analysis of the produced pyro-oils identified functional groups such as phenols, alcohols, ketones, aldehydes, and alkanes. The study also investigated the effects of feedstock composition and temperature on the synergistic effect of pyro-oil yield. The highest CVs of pyro-oil were 50.28 MJ/kg from waste plastics, 47.36 MJ/kg from waste tires, and 43.39 MJ/kg from the blends at a 2:1:1 mass ratio at 550 °C. The highest pyro-oil yields were wt % from waste tires with 46.7 and 53.3 wt % at 500 and 550 °C, respectively, and 41.7 wt % from the blends at a 2:1:1 mass ratio at 550 °C. Optimal operating conditions were determined to be 550 °C with a 2:1:1 mass ratio for maximizing pyro-oil yield. Overall, this study provides valuable insights into the potential of combining waste tires, waste plastics, and biomass for pyro-oil production, emphasizing the importance of specific operating conditions and feedstock ratios to achieve optimal results.